Investments in Joint Ventures Investments in Joint Ventures - Condensed Combined Balance Sheets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010
Schedule of Equity Method Investments [Line Items]
Gross Investment in Real Estate	$ 3,119,547		$ 3,130,942		$ 3,115,050	$ 3,140,649
Less: Accumulated Depreciation	(748,044)		(732,635)
Net Investment in Real Estate	2,371,503		2,388,813
Real Estate and Other Assets Held for Sale, Net of Accumulated Depreciation and Amortization of $40,387 and $0	0		6,765
Total Assets	2,597,510		2,608,842
Indebtedness	1,297,671
Total Liabilities and Equity	2,597,510		2,608,842
Carrying Value of the Company's Investments in Joint Ventures	907		1,012
Corporate Joint Venture [Member]
Schedule of Equity Method Investments [Line Items]
Gross Investment in Real Estate	28,389		115,488
Less: Accumulated Depreciation	(4,253)		(38,535)
Net Investment in Real Estate	24,136		76,953
Real Estate and Other Assets Held for Sale, Net of Accumulated Depreciation and Amortization of $40,387 and $0	48,408		0
Other Assets	7,690		17,327
Total Assets	80,234		94,280
Indebtedness	24,656		81,764
Other Liabilities	1,615		4,817
Indebtedness, Accrued Interest Expense and Leasing Intangibles Held for Sale, Net of Accumulated Amortization of $3,208 and $0	48,651		0
Equity	5,312		7,699
Total Liabilities and Equity	80,234		94,280
Company's Share of Equity	896		1,252
Basis Differentials	(200)	[1]	(448)	[1]
Carrying Value of the Company's Investments in Joint Ventures	$ 696		$ 804

[1] This amount represents the aggregate difference between our historical cost basis and the basis reflected at the joint venture level. Basis differentials are primarily comprised of impairments we recorded to reduce certain of our investments in the 2003 Net Lease Joint Venture to fair value and certain deferred fees which are not reflected at the joint venture level.