Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 1,263,448	$ 1,221,560
Less: accumulated depreciation	(451,443)	(432,123)
Total property and equipment, net	812,005	789,437
Buildings
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	657,438	634,061
Furniture and equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	280,908	256,509
Software
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	162,601	151,890
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	103,428	117,806
Computers
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 59,073	$ 61,294