| 
   
  
| 
   
 | 
   
 | 
 Operating Office Property Segments 
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
 
| 
   
 | 
   
 | 
 Baltimore/ 
Washington 
Corridor 
 | 
   
 | 
 Northern 
Virginia 
 | 
   
 | 
 San 
Antonio 
 | 
   
 | 
 Washington, 
DC - Capitol 
Riverfront 
 | 
   
 | 
 St. Mary’s &  
King George 
Counties 
 | 
   
 | 
 Greater 
Baltimore 
 | 
   
 | 
 Suburban 
Maryland 
 | 
   
 | 
 Colorado 
Springs 
 | 
   
 | 
 Greater 
Philadelphia 
 | 
   
 | 
 Other 
 | 
   
 | 
 Operating 
Wholesale 
Data Center 
 | 
   
 | 
 Total 
 | 
   
 | 
 
| 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
 
| 
 Three Months Ended March 31, 2012 
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
 
| 
 Revenues from real estate operations 
 | 
   
 | 
 $ 
 | 
 56,250 
 | 
   
 | 
 $ 
 | 
 18,560 
 | 
   
 | 
 $ 
 | 
 7,608 
 | 
   
 | 
 $ 
 | 
 3,894 
 | 
   
 | 
 $ 
 | 
 4,212 
 | 
   
 | 
 $ 
 | 
 15,372 
 | 
   
 | 
 $ 
 | 
 5,749 
 | 
   
 | 
 $ 
 | 
 6,453 
 | 
   
 | 
 $ 
 | 
 2,172 
 | 
   
 | 
 $ 
 | 
 3,618 
 | 
   
 | 
 $ 
 | 
 1,416 
 | 
   
 | 
 $ 
 | 
 125,304 
 | 
   
 | 
 
| 
 Property operating expenses 
 | 
   
 | 
 20,151 
 | 
   
 | 
 7,400 
 | 
   
 | 
 3,817 
 | 
   
 | 
 1,910 
 | 
   
 | 
 1,258 
 | 
   
 | 
 5,890 
 | 
   
 | 
 2,521 
 | 
   
 | 
 2,385 
 | 
   
 | 
 615 
 | 
   
 | 
 1,233 
 | 
   
 | 
 1,207 
 | 
   
 | 
 48,387 
 | 
   
 | 
 
| 
 NOI from real estate operations 
 | 
   
 | 
 $ 
 | 
 36,099 
 | 
   
 | 
 $ 
 | 
 11,160 
 | 
   
 | 
 $ 
 | 
 3,791 
 | 
   
 | 
 $ 
 | 
 1,984 
 | 
   
 | 
 $ 
 | 
 2,954 
 | 
   
 | 
 $ 
 | 
 9,482 
 | 
   
 | 
 $ 
 | 
 3,228 
 | 
   
 | 
 $ 
 | 
 4,068 
 | 
   
 | 
 $ 
 | 
 1,557 
 | 
   
 | 
 $ 
 | 
 2,385 
 | 
   
 | 
 $ 
 | 
 209 
 | 
   
 | 
 $ 
 | 
 76,917 
 | 
   
 | 
 
| 
 Additions to long-lived assets 
 | 
   
 | 
 $ 
 | 
 1,864 
 | 
   
 | 
 $ 
 | 
 1,661 
 | 
   
 | 
 $ 
 | 
 — 
 | 
   
 | 
 $ 
 | 
 (729 
 | 
 ) 
 | 
 $ 
 | 
 167 
 | 
   
 | 
 $ 
 | 
 719 
 | 
   
 | 
 $ 
 | 
 771 
 | 
   
 | 
 $ 
 | 
 99 
 | 
   
 | 
 $ 
 | 
 — 
 | 
   
 | 
 $ 
 | 
 26 
 | 
   
 | 
 $ 
 | 
 — 
 | 
   
 | 
 $ 
 | 
 4,578 
 | 
   
 | 
 
| 
 Transfers from non-operating properties 
 | 
   
 | 
 $ 
 | 
 25,594 
 | 
   
 | 
 $ 
 | 
 — 
 | 
   
 | 
 $ 
 | 
 362 
 | 
   
 | 
 $ 
 | 
 — 
 | 
   
 | 
 $ 
 | 
 556 
 | 
   
 | 
 $ 
 | 
 365 
 | 
   
 | 
 $ 
 | 
 335 
 | 
   
 | 
 $ 
 | 
 316 
 | 
   
 | 
 $ 
 | 
 7,303 
 | 
   
 | 
 $ 
 | 
 — 
 | 
   
 | 
 $ 
 | 
 — 
 | 
   
 | 
 $ 
 | 
 34,831 
 | 
   
 | 
 
| 
 Segment assets at March 31, 2012 
 | 
   
 | 
 $ 
 | 
 1,231,949 
 | 
   
 | 
 $ 
 | 
 480,457 
 | 
   
 | 
 $ 
 | 
 120,024 
 | 
   
 | 
 $ 
 | 
 108,649 
 | 
   
 | 
 $ 
 | 
 99,946 
 | 
   
 | 
 $ 
 | 
 370,754 
 | 
   
 | 
 $ 
 | 
 147,197 
 | 
   
 | 
 $ 
 | 
 181,241 
 | 
   
 | 
 $ 
 | 
 109,432 
 | 
   
 | 
 $ 
 | 
 114,108 
 | 
   
 | 
 $ 
 | 
 43,390 
 | 
   
 | 
 $ 
 | 
 3,007,147 
 | 
   
 | 
 
| 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
 
| 
 Three Months Ended March 31, 2011 
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
   
 | 
 
| 
 Revenues from real estate operations 
 | 
   
 | 
 $ 
 | 
 53,252 
 | 
   
 | 
 $ 
 | 
 18,274 
 | 
   
 | 
 $ 
 | 
 7,663 
 | 
   
 | 
 $ 
 | 
 4,590 
 | 
   
 | 
 $ 
 | 
 3,534 
 | 
   
 | 
 $ 
 | 
 17,612 
 | 
   
 | 
 $ 
 | 
 5,609 
 | 
   
 | 
 $ 
 | 
 5,920 
 | 
   
 | 
 $ 
 | 
 1,939 
 | 
   
 | 
 $ 
 | 
 2,838 
 | 
   
 | 
 $ 
 | 
 1,210 
 | 
   
 | 
 $ 
 | 
 122,441 
 | 
   
 | 
 
| 
 Property operating expenses 
 | 
   
 | 
 21,058 
 | 
   
 | 
 7,590 
 | 
   
 | 
 3,813 
 | 
   
 | 
 1,627 
 | 
   
 | 
 1,014 
 | 
   
 | 
 8,452 
 | 
   
 | 
 2,661 
 | 
   
 | 
 2,343 
 | 
   
 | 
 418 
 | 
   
 | 
 467 
 | 
   
 | 
 709 
 | 
   
 | 
 50,152 
 | 
   
 | 
 
| 
 NOI from real estate operations 
 | 
   
 | 
 $ 
 | 
 32,194 
 | 
   
 | 
 $ 
 | 
 10,684 
 | 
   
 | 
 $ 
 | 
 3,850 
 | 
   
 | 
 $ 
 | 
 2,963 
 | 
   
 | 
 $ 
 | 
 2,520 
 | 
   
 | 
 $ 
 | 
 9,160 
 | 
   
 | 
 $ 
 | 
 2,948 
 | 
   
 | 
 $ 
 | 
 3,577 
 | 
   
 | 
 $ 
 | 
 1,521 
 | 
   
 | 
 $ 
 | 
 2,371 
 | 
   
 | 
 $ 
 | 
 501 
 | 
   
 | 
 $ 
 | 
 72,289 
 | 
   
 | 
 
| 
 Additions to long-lived assets 
 | 
   
 | 
 $ 
 | 
 6,405 
 | 
   
 | 
 $ 
 | 
 2,033 
 | 
   
 | 
 $ 
 | 
 — 
 | 
   
 | 
 $ 
 | 
 156 
 | 
   
 | 
 $ 
 | 
 380 
 | 
   
 | 
 $ 
 | 
 8,088 
 | 
   
 | 
 $ 
 | 
 1,052 
 | 
   
 | 
 $ 
 | 
 736 
 | 
   
 | 
 $ 
 | 
 (4 
 | 
 ) 
 | 
 $ 
 | 
 (646 
 | 
 ) 
 | 
 $ 
 | 
 — 
 | 
   
 | 
 $ 
 | 
 18,200 
 | 
   
 | 
 
| 
 Transfers from non-operating properties 
 | 
   
 | 
 $ 
 | 
 19,883 
 | 
   
 | 
 $ 
 | 
 (7 
 | 
 ) 
 | 
 $ 
 | 
 600 
 | 
   
 | 
 $ 
 | 
 — 
 | 
   
 | 
 $ 
 | 
 — 
 | 
   
 | 
 $ 
 | 
 4,247 
 | 
   
 | 
 $ 
 | 
 354 
 | 
   
 | 
 $ 
 | 
 — 
 | 
   
 | 
 $ 
 | 
 (2,474 
 | 
 ) 
 | 
 $ 
 | 
 — 
 | 
   
 | 
 $ 
 | 
 6,654 
 | 
   
 | 
 $ 
 | 
 29,257 
 | 
   
 | 
 
| 
 Segment assets at March 31, 2011 
 | 
   
 | 
 $ 
 | 
 1,199,244 
 | 
   
 | 
 $ 
 | 
 488,599 
 | 
   
 | 
 $ 
 | 
 115,221 
 | 
   
 | 
 $ 
 | 
 117,758 
 | 
   
 | 
 $ 
 | 
 87,690 
 | 
   
 | 
 $ 
 | 
 479,474 
 | 
   
 | 
 $ 
 | 
 145,913 
 | 
   
 | 
 $ 
 | 
 214,111 
 | 
   
 | 
 $ 
 | 
 96,372 
 | 
   
 | 
 $ 
 | 
 83,247 
 | 
   
 | 
 $ 
 | 
 30,714 
 | 
   
 | 
 $ 
 | 
 3,058,343 
 | 
 
 
 | 
 
 
 |