Business Segments - Revenue and Long-Lived Assets by Geographic Location (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Service revenues	$ 6,461,444	$ 5,109,000	$ 6,074,432
Assets, long-lived	93,403	109,817	128,385
Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Service revenues	5,006,525	3,984,742	4,708,715
Assets, long-lived	76,757	88,117	99,365
Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Service revenues	1,454,919	1,124,258	1,365,717
Assets, long-lived	$ 16,646	$ 21,700	$ 29,020