Property and Equipment (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property and Equipment [Abstract]
Property and equipment		$ 787,534	$ 750,826
Less: accumulated depreciation		(322,999)	(286,239)
Property and equipment, net		464,535	464,587	$ 444,732
Depreciation expense		56,400	58,300	60,800
Impairment charges		48,551	0	$ 0
Land [Member]
Property and Equipment [Abstract]
Property and equipment		35,709	33,667
Buildings [Member]
Property and Equipment [Abstract]
Property and equipment		295,748	274,632
Construction in Progress [Member]
Property and Equipment [Abstract]
Property and equipment	[1]	18,153	53,125
Furniture and Fixtures [Member]
Property and Equipment [Abstract]
Property and equipment		118,149	95,378
Computers and Equipment [Member]
Property and Equipment [Abstract]
Property and equipment		160,873	156,994
Leasehold Improvements [Member]
Property and Equipment [Abstract]
Property and equipment		147,604	123,479
Scanners [Member]
Property and Equipment [Abstract]
Property and equipment		8,986	11,212
Vehicles [Member]
Property and Equipment [Abstract]
Property and equipment		2,312	2,339
Internal-Use Software Development Costs [Member]
Property and Equipment [Abstract]
Property and equipment		$ 8,700	$ 43,400

[1] Construction in progress includes $8.7 million and $43.4 million as of December 31, 2018 and 2017, respectively, of eligible capitalized internal-use software development costs which will be reclassified to computers and equipment when placed into service.