Related Party Transactions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Rent expense	$ 58,100	$ 45,400	$ 40,300
Future minimum lease commitments	445,975
Affiliates of Chairman of Board of Directors
Related Party Transaction [Line Items]
Rent expense	1,300	$ 1,200	$ 1,200
Future minimum lease commitments	$ 3,200