Segment Disclosure (Details 2) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010	Dec. 31, 2009
Reconciliation to Consolidated Assets:
Total assets for reportable segments	$ 3,264,787	$ 2,816,565
Other unallocated asset:
Cash and cash equivalents	25,412	14,840	29,428	9,883
Restricted cash	1,349	1,461
Marketable securities	5,654	4,902
Deferred financing costs, net	18,910	16,447
Prepaid expenses and other assets, net	25,559	8,097
Total Assets	3,264,787	2,816,565
Total Segments [Member]
Reconciliation to Consolidated Assets:
Total assets for reportable segments	3,187,903	2,770,818
Other unallocated asset:
Total Assets	$ 3,187,903	$ 2,770,818