Consolidated Statements of Operations and Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Statement [Abstract]
Revenue	$ 1,202,388	$ 1,113,382	$ 1,109,435
Cost of services	422,006	408,043	439,742
Gross profit	780,382	705,339	669,693
Operating expenses:
Sales and marketing	362,432	357,813	315,195
General and administrative	216,406	153,902	177,574
Impairment charges	102,222	3,611	24,911
Total operating expenses	681,060	515,326	517,680
Operating income	99,322	190,013	152,013
Other income (expense):
Interest expense	(56,902)	(48,867)	(51,537)
Interest expense, related party	(3,505)	(17,507)	(17,002)
Other components of net periodic pension benefit (cost)	44,612	14,829	(42,236)
Other income (expense)	15,448	(4,154)	0
Income before income tax (expense) benefit	98,975	134,314	41,238
Income tax (expense) benefit	(44,627)	(32,737)	107,983
Net income	54,348	101,577	149,221
Other comprehensive income (loss):
Foreign currency translation adjustment, net of tax	(8,214)	(8,047)	0
Comprehensive income	$ 46,134	$ 93,530	$ 149,221
Earnings Per Share [Abstract]
Basic (in USD per share)	$ 1.58	$ 3.02	$ 4.73
Diluted (in USD per share)	$ 1.49	$ 2.78	$ 4.42
Weighted-average shares used in computing basic and diluted net income per common share:
Basic (in shares)	34,336,493	33,607,446	31,522,845
Diluted (in shares)	36,506,095	36,495,746	33,795,594