Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Operating revenue	$ 1,642,375	$ 1,440,873	$ 1,436,370
Cost of services (exclusive of depreciation and amortization)	597,022	632,117	662,293
Selling, general and administrative expenses	537,617	463,787	427,878
Depreciation and amortization	174,445	175,100	181,142
Impairment loss	2,309	47,834	7,687
Total operating expenses	1,311,393	1,318,838	1,279,000
Operating income	330,982	122,035	157,370
Interest expense:
Interest income	724	2,136	1,577
Interest expense	69,900	78,293	75,551
Total interest expense, net	(69,176)	(76,157)	(73,974)
Tax indemnification release	0	(13,394)	0
Gain/(loss) on investments and other, net	42,151	(1,077)	18,708
Income from continuing operations before equity in earnings of affiliates and income taxes	303,957	31,407	102,104
Provision/(benefit) for income taxes	41,566	(1,807)	29,587
Income from continuing operations before equity in earnings of affiliates	262,391	33,214	72,517
Equity in earnings of affiliates, net of tax	1,859	556	1,493
Net income from continuing operations	264,250	33,770	74,010
Income from discontinued operations, net of tax	34,363	15,610	47,854
Gain from sale of discontinued operations, net of tax	2,742	0	0
Net income	$ 301,355	$ 49,380	$ 121,864
Basic income per share:
Net income from continuing operations (usd per share)	$ 3.36	$ 0.42	$ 0.92
Income from discontinued operations, net of tax (usd per share)	0.44	0.20	0.59
Gain from sale of discontinued operations, net of tax (usd per share)	0.03	0	0
Net income (usd per share)	3.83	0.62	1.51
Diluted income per share:
Net income from continuing operations (usd per share)	3.28	0.42	0.90
Income from discontinued operations, net of tax (usd per share)	0.43	0.19	0.58
Gain from sale of discontinued operations, net of tax (usd per share)	0.03	0	0
Net income (usd per share)	$ 3.74	$ 0.61	$ 1.48
Weighted-average common shares outstanding:
Basic (in shares)	78,542	79,885	80,854
Diluted (in shares)	80,495	81,021	82,275