Schedule III - Real Estate and Accumulated Depreciation Summary of Transactions (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Investment in Real Estate, balance at beginning of period	$ 3,049,672	$ 2,972,528	$ 2,888,791
Additions through Capital Expenditures	30,376	77,233	89,008
Sale of real estate for cash	(554)	(81)	(853)
Reclassifications and other	(592)	(8)	(4,418)
Investment in Real Estate, balance at end of period	3,078,902	3,049,672	2,972,528
Accumulated Depreciation, balance at beginning of period	(680,965)	(607,771)	(539,094)
Depreciation	(75,069)	(73,260)	(69,143)
Disposals	273	66	466
Accumulated Depreciation, balance at end of period	$ (755,761)	$ (680,965)	$ (607,771)