Business Segments and Geographic Information Geographic Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 01, 2012
Geographical Information
Revenues	$ 427,740	$ 457,900	$ 412,843	$ 393,137	$ 383,548	$ 379,842	$ 381,653	$ 377,031	$ 1,691,620	$ 1,522,074	$ 1,479,062
Property and equipment, net	1,772,166				1,727,798				1,772,166	1,727,798		1,687,159
U.S. operations
Geographical Information
Revenues									1,438,144	1,314,425	1,267,335
Property and equipment, net	1,765,391				1,721,761				1,765,391	1,721,761		1,680,038
Australia operations
Geographical Information
Revenues									210,577	158,028	159,444
Property and equipment, net	5,923				4,828				5,923	4,828		5,634
South African operations
Geographical Information
Revenues									16,831	17,992	20,029
Property and equipment, net	127				158				127	158		234
United Kingdom operations
Geographical Information
Revenues									26,068	31,629	32,254
Property and equipment, net	$ 725				$ 1,051				$ 725	$ 1,051		$ 1,253