Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Operating revenues	$ 436,727	$ 375,571	$ 1,174,733	$ 1,088,032
Cost of services (excluding depreciation and amortization shown below)	154,192	164,715	439,032	486,973
Selling, general and administrative expenses	165,742	106,600	393,247	348,788
Depreciation and amortization	43,610	42,389	130,639	132,767
Impairment loss	0	0	1,228	47,834
Total operating expenses	363,544	313,704	964,146	1,016,362
Operating income	73,183	61,867	210,587	71,670
Interest expense:
Interest income	100	349	611	1,728
Interest expense	17,021	19,852	52,958	59,137
Total interest expense, net	(16,921)	(19,503)	(52,347)	(57,409)
Gain/(loss) on investments and other, net	35,674	227	37,154	(2,116)
Tax indemnification release	0	0	0	(13,394)
Income/(loss) from continuing operations before equity in earnings of affiliates and income taxes	91,936	42,591	195,394	(1,249)
(Benefit)/provision for income taxes	(9,560)	11,530	19,433	(8,976)
Income from continuing operations before equity in earnings of affiliates	101,496	31,061	175,961	7,727
Equity in earnings of affiliates, net of tax	971	607	1,859	498
Net income from continuing operations	102,467	31,668	177,820	8,225
Income/(loss) from discontinued operations, net of tax	10,679	(8,485)	28,149	11,073
Net income	$ 113,146	$ 23,183	$ 205,969	$ 19,298
Basic income per share:
Net income from continuing operations (usd per share)	$ 1.29	$ 0.40	$ 2.24	$ 0.10
Loss from discontinued operations, net of tax (usd per share)	0.13	(0.11)	0.35	0.14
Net (loss)/income (usd per share)	1.42	0.29	2.59	0.24
Diluted income per share:
Net income from continuing operations (usd per share)	1.26	0.39	2.19	0.10
Loss from discontinued operations, net of tax (usd per share)	0.13	(0.10)	0.35	0.14
Net (loss)/income (usd per share)	$ 1.39	$ 0.29	$ 2.54	$ 0.24
Weighted-average common shares outstanding:
Basic (in shares)	79,467	79,761	79,300	80,138
Diluted (in shares)	81,402	80,914	81,136	81,205