SCHEDULE III-Consolidated Real Estate and Accumulated Depreciation Rollforward (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Real estate assets
Balance, beginning of period	$ 1,938,676		$ 1,687,276		$ 1,165,097
Property acquisitions	0		270,082		563,858
Improvements	60,677	[1]	41,303	[1]	13,595	[1]
Cost of Real Estate Sold	0		(57,188)		(37,599)
Other	(3,936)	[1],[2]	(2,797)	[1],[2]	(17,675)	[1],[2]
Balance, end of period	1,995,417		1,938,676		1,687,276
Accumulated depreciation
Balance, beginning of period	270,494		234,595		221,997
Additions-depreciation	51,949	[1]	47,792	[1]	42,498	[1]
Cost of Real Estate Sold	0		(9,216)		(12,225)
Other	(3,862)	[1],[2]	(2,677)	[1],[2]	(17,675)	[1],[2]
Balance, end of period	$ 318,581		$ 270,494		$ 234,595

[1] Includes discontinued operations for 160 King Street, which was sold on December 4, 2012 and Valencia Corporate Center, which was sold on August 30, 2011.

[2] Other deductions for the years ended December 31, 2013, 2012 and 2011 represent the write-off of fully depreciated assets.