CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (unaudited) - USD ($) $ in Thousands	Total	Class A Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Treasury Stock [Member] Class A Common Stock [Member]	Noncontrolling interests [Member]
Balance at Dec. 31, 2018	$ 1,868,984	$ 473	$ 1,351,931	$ 620,371	$ (14,316)	$ (105,685)		$ 16,210
Balance, Shares at Dec. 31, 2018		47,291,463
Balance, Shares at Dec. 31, 2018						1,665,217
Stock-based compensation expense	29,030		29,030
Vesting of restricted stock units and exercise of stock options	(8,064)		(34,450)			$ 26,386
Vesting of restricted stock units and exercise of stock options, shares						512,539
Common stock dividends declared	(62,062)			(62,062)
Purchase of noncontrolling interest from a consolidated variable interest entity	(6,500)							(6,500)
Noncontrolling interest from a business combination	6,201							6,201
Net income (loss)	122,444			117,047				5,397
Balance at Sep. 30, 2019	1,950,033	$ 473	1,346,511	675,356	(14,316)	$ (79,299)		21,308
Balance, Shares at Sep. 30, 2019		47,291,463
Balance, Shares at Sep. 30, 2019						1,152,678
Balance at Jun. 30, 2019	1,958,217	$ 473	1,337,057	701,946	(14,316)	$ (81,381)		14,438
Balance, Shares at Jun. 30, 2019		47,291,463
Balance, Shares at Jun. 30, 2019						1,188,353
Stock-based compensation expense	11,270		11,270
Vesting of restricted stock units and exercise of stock options	266		(1,816)			$ 2,082
Vesting of restricted stock units and exercise of stock options, shares						35,675
Common stock dividends declared	(20,743)			(20,743)
Noncontrolling interest from a business combination	6,201							6,201
Net income (loss)	(5,178)			(5,847)				669
Balance at Sep. 30, 2019	1,950,033	$ 473	1,346,511	675,356	(14,316)	$ (79,299)		21,308
Balance, Shares at Sep. 30, 2019		47,291,463
Balance, Shares at Sep. 30, 2019						1,152,678
Balance at Dec. 31, 2019	$ 2,053,493	$ 473	1,353,729	778,833	19,850	$ (121,388)		21,996
Balance, Shares at Dec. 31, 2019		47,291,463
Balance, Shares at Dec. 31, 2019	(1,541,675)					1,541,675
Purchase of treasury stock	$ (197,600)					$ (197,600)	$ (197,600)
Purchase of treasury stock, shares						(2,250,000)
Stock-based compensation expense	35,917		35,917
Vesting of restricted stock units and exercise of stock options	(4,610)		(36,893)			$ 32,283
Vesting of restricted stock units and exercise of stock options, shares						535,227
Common stock dividends declared	(76,380)			(76,380)
Contribution from a noncontrolling interest	138							138
Disposal of an entity	(1,390)		(1,381)	(9)
Net income (loss)	445,148			447,194				(2,046)
Balance at Sep. 30, 2020	$ 2,254,716	$ 473	1,351,372	1,149,638	19,850	$ (286,705)		20,088
Balance, Shares at Sep. 30, 2020		47,291,463
Balance, Shares at Sep. 30, 2020	(3,256,448)					3,256,448
Balance at Jun. 30, 2020	$ 2,201,777	$ 473	1,340,526	984,316	19,850	$ (164,847)		21,459
Balance, Shares at Jun. 30, 2020		47,291,463
Balance, Shares at Jun. 30, 2020						2,004,823
Purchase of treasury stock	(125,013)					$ (125,013)	$ (125,000)
Purchase of treasury stock, shares						(1,300,000)
Stock-based compensation expense	12,483		12,483
Vesting of restricted stock units and exercise of stock options	1,518		(1,637)			$ 3,155
Vesting of restricted stock units and exercise of stock options, shares						48,375
Common stock dividends declared	(25,362)			(25,362)
Net income (loss)	189,313			190,684				(1,371)
Balance at Sep. 30, 2020	$ 2,254,716	$ 473	$ 1,351,372	$ 1,149,638	$ 19,850	$ (286,705)		$ 20,088
Balance, Shares at Sep. 30, 2020		47,291,463
Balance, Shares at Sep. 30, 2020	(3,256,448)					3,256,448