Property and Equipment (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Acquired Indefinite-lived Intangible Assets [Line Items]
Leasehold interests	$ 473,865,000	$ 437,397,000
Property and Equipment (Textual) [Abstract]
Net carrying amount of capitalized software	14,200,000	14,900,000
Depreciation expense	30,000,000	28,400,000	27,300,000
Impairment losses related to property and equipment			117,000
Impairment losses recorded	0	0	302,000
Leasehold Land Interests [Member]
Acquired Indefinite-lived Intangible Assets [Line Items]
Leasehold interests	$ 10,600,000	$ 2,600,000