Condensed Consolidated Statement of Changes in Stockholder's Equity - USD ($) $ in Thousands	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income, net	Redeemable Noncontrolling Interests	Total
Beginning balance at Dec. 31, 2018	$ 1,200	$ (720,100)	$ 2,660,200	$ 1,288,200	$ 11,500	$ 9,400	$ 3,241,000
Increase (Decrease) in Stockholders' Equity
Cash dividends on common stock				(34,800)			(34,800)
Stock-based compensation			5,400				5,400
Exercise of common stock options			8,100				8,100
Repurchases of common stock from employee stock plans		(10,000)					(10,000)
Purchase of common stock		(35,000)					(35,000)
Shares issued under employee stock purchase plan		800					800
Net income excluding noncontrolling interest				95,400			95,400
Other comprehensive income (loss)					14,700		14,700
Net loss attributable to redeemable noncontrolling interest						(200)
Redemption value adjustment of redeemable noncontrolling interest				(200)		200	(200)
Ending balance at Mar. 31, 2019	1,200	(764,300)	2,673,700	1,348,600	26,200	9,400	3,285,400
Beginning balance at Dec. 31, 2018	1,200	(720,100)	2,660,200	1,288,200	11,500	9,400	3,241,000
Increase (Decrease) in Stockholders' Equity
Net income excluding noncontrolling interest							182,600
Ending balance at Jun. 30, 2019	1,200	(764,600)	2,680,400	1,401,900	8,100	5,800	3,327,000
Beginning balance at Mar. 31, 2019	1,200	(764,300)	2,673,700	1,348,600	26,200	9,400	3,285,400
Increase (Decrease) in Stockholders' Equity
Cash dividends on common stock				(34,800)			(34,800)
Stock-based compensation			6,300				6,300
Exercise of common stock options			400				400
Repurchases of common stock from employee stock plans		(400)					(400)
Purchase of common stock							(10)
Shares issued under employee stock purchase plan		100					100
Net income excluding noncontrolling interest				88,300			88,300
Other comprehensive income (loss)					(18,100)		(18,100)
Net loss attributable to redeemable noncontrolling interest						(3,800)
Redemption value adjustment of redeemable noncontrolling interest				(200)		200	(200)
Ending balance at Jun. 30, 2019	1,200	(764,600)	2,680,400	1,401,900	8,100	$ 5,800	3,327,000
Beginning balance at Dec. 31, 2019	1,200	(887,100)	2,691,300	1,512,600	37,600		3,355,600
Increase (Decrease) in Stockholders' Equity
Cash dividends on common stock				(40,000)			(40,000)
Stock-based compensation			8,300				8,300
Repurchases of common stock from employee stock plans		(13,900)					(13,900)
Purchase of common stock		(119,500)					(119,500)
Shares issued under employee stock purchase plan			100				100
Net income excluding noncontrolling interest				157,400			157,400
Other comprehensive income (loss)					(37,500)		(37,500)
Ending balance at Mar. 31, 2020	1,200	(1,020,500)	2,699,700	1,629,600	100		3,310,100
Beginning balance at Dec. 31, 2019	1,200	(887,100)	2,691,300	1,512,600	37,600		3,355,600
Increase (Decrease) in Stockholders' Equity
Net income excluding noncontrolling interest							271,000
Other comprehensive income (loss)					(40,200)
Ending balance at Jun. 30, 2020	1,200	(1,120,500)	2,704,500	1,703,700	(2,600)		3,286,300
Increase (Decrease) in Stockholders' Equity
Transition adjustment for adoption of Current Expected Credit Losses standard at January 1, 2020				(400)			(400)
Beginning balance at Mar. 31, 2020	1,200	(1,020,500)	2,699,700	1,629,600	100		3,310,100
Increase (Decrease) in Stockholders' Equity
Cash dividends on common stock				(39,500)			(39,500)
Stock-based compensation			4,600				4,600
Exercise of common stock options			200				200
Repurchases of common stock from employee stock plans		(200)					(200)
Purchase of common stock		(99,800)					(99,800)
Net income excluding noncontrolling interest				113,600			113,600
Other comprehensive income (loss)					(2,700)		(2,700)
Ending balance at Jun. 30, 2020	$ 1,200	$ (1,120,500)	$ 2,704,500	$ 1,703,700	$ (2,600)		$ 3,286,300