Significant Accounting Policies (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Right-of-use assets	$ 419,247	$ 438,700
Operating lease liabilities	539,096	574,500
Financing right-of-use assets	2,070	2,400
Finance lease liabilities	$ 2,074	2,400
Deferred rent		50,000
Restructuring reserve		$ 85,800	$ 85,800