Property and Equipment (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property and Equipment [Abstract]
Property and equipment		$ 678,457	$ 666,130
Less: accumulated depreciation		(233,725)	(211,593)
Property and equipment, net		444,732	454,537
Depreciation expense		60,800	61,600	$ 46,500
Land [Member]
Property and Equipment [Abstract]
Property and equipment		33,158	33,610
Buildings [Member]
Property and Equipment [Abstract]
Property and equipment		266,436	272,208
Construction in Progress [Member]
Property and Equipment [Abstract]
Property and equipment	[1]	31,124	7,827
Furniture and Fixtures [Member]
Property and Equipment [Abstract]
Property and equipment		82,194	81,274
Computers and Equipment [Member]
Property and Equipment [Abstract]
Property and equipment		143,014	141,079
Leasehold Improvements [Member]
Property and Equipment [Abstract]
Property and equipment		109,863	116,120
Scanners [Member]
Property and Equipment [Abstract]
Property and equipment		10,578	11,805
Vehicles [Member]
Property and Equipment [Abstract]
Property and equipment		2,090	2,207
Internal-Use Software Development Costs [Member]
Property and Equipment [Abstract]
Property and equipment		$ 25,800	$ 700

[1] Construction in progress includes $0.7 million and $25.8 million as of December 31, 2015 and 2016, respectively, of eligible capitalized internal-use software development costs which will be reclassified to computers and equipment when placed into service.