Leases - Net Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Leases [Abstract]
Operating lease cost	$ 32,620	$ 35,173	$ 65,485	$ 73,134
Variable lease cost	4,121	3,973	8,423	8,376
Sublease income	(10,584)	(10,719)	(20,923)	(21,810)
Total lease cost, net	26,157	28,427	52,985	59,700
Cash paid for amounts included in the measurement of operating lease liabilities	35,324	34,026	70,251	68,962
Cash receipts from sublease arrangements	10,364	9,503	20,459	18,920
Right-of-use assets obtained in exchange for new operating lease liabilities	2,248	3,616	9,294	18,535
Cost for subleasing activities	$ 10,700	$ 10,600	$ 21,100	$ 21,200