SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION Reconciliation of Real Estate Properties (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Balance at beginning of year	$ 1,098,761	$ 950,710	$ 817,170
Other improvements	72,633	42,167	133,540
Property Acquired	324,348	105,884	0
Balance at end of year	$ 1,495,742	$ 1,098,761	$ 950,710