Consolidated Statements of Equity Consolidated Statements of Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid- In Capital	Retained Earnings	AOCI Attributable to Parent [Member]	Non Controlling Interest
Beginning balance (in shares) at Dec. 31, 2017		63,075
Beginning balance at Dec. 31, 2017	$ 931,659	$ 631	$ 733,894	$ 242,763	$ (45,629)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee stock compensation (in shares)		(5)
Employee stock compensation	12,032		12,032
Deferred compensation	420		(392)	812
Proceeds from stock issuances under employee plans (in shares)		161
Proceeds from stock issuances under employee plans	11,905	$ 2	11,903
Cash dividends declared	(37,796)			(37,796)
Repurchase and retirement of common shares (in shares)		(133)
Repurchase and retirement of common shares	(14,987)	$ (2)	(1,549)	(13,436)
Other activity	(1,077)			(1,077)
Net income	55,714			55,714
Other comprehensive loss	15,592				15,592
Ending balance (in shares) at Mar. 31, 2018		63,098
Ending balance at Mar. 31, 2018	973,462	$ 631	755,888	246,980	(30,037)	0
Beginning balance (in shares) at Dec. 31, 2017		63,075
Beginning balance at Dec. 31, 2017	931,659	$ 631	733,894	242,763	(45,629)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	243,783
Ending balance (in shares) at Sep. 30, 2018		61,773
Ending balance at Sep. 30, 2018	898,252	$ 618	799,607	152,282	(54,534)	279
Beginning balance (in shares) at Mar. 31, 2018		63,098
Beginning balance at Mar. 31, 2018	973,462	$ 631	755,888	246,980	(30,037)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee stock compensation (in shares)		12
Employee stock compensation	20,969		20,969
Deferred compensation	(1,470)		(617)	(853)
Proceeds from stock issuances under employee plans (in shares)		533
Proceeds from stock issuances under employee plans	31,543	$ 5	31,538
Cash dividends declared	(37,898)			(37,898)
Repurchase and retirement of common shares (in shares)		(1,429)
Repurchase and retirement of common shares	(177,380)	$ (14)	(16,630)	(160,736)
Net income	92,540			92,540
Other comprehensive loss	(24,256)				(24,256)
Ending balance (in shares) at Jun. 30, 2018		62,214
Ending balance at Jun. 30, 2018	877,510	$ 622	791,148	140,033	(54,293)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee stock compensation (in shares)		17
Employee stock compensation	10,218		10,218
Deferred compensation	3,144		714	2,430
Proceeds from stock issuances under employee plans (in shares)		49
Proceeds from stock issuances under employee plans	3,431	$ 1	3,430
Cash dividends declared	(37,054)			(37,054)
Repurchase and retirement of common shares (in shares)		(507)
Repurchase and retirement of common shares	(54,564)	$ (5)	(5,903)	(48,656)
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	279
Net income	95,529			95,529
Other comprehensive loss	(241)				(241)
Ending balance (in shares) at Sep. 30, 2018		61,773
Ending balance at Sep. 30, 2018	898,252	$ 618	799,607	152,282	(54,534)	279
Beginning balance (in shares) at Dec. 31, 2018		60,890
Beginning balance at Dec. 31, 2018	867,015	$ 609	807,986	121,114	(62,973)	279
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee stock compensation (in shares)		214
Employee stock compensation	12,091	$ 2	12,089
Deferred compensation	(1,887)		(1,541)	(346)
Proceeds from stock issuances under employee plans (in shares)		18
Proceeds from stock issuances under employee plans	3,207		3,207
Cash dividends declared	(37,144)			(37,144)
Repurchase and retirement of common shares (in shares)		(71)
Repurchase and retirement of common shares	(6,110)	$ 0	(953)	(5,157)
Other activity	0	$ 0		668	(668)	0
Net income	48,396			48,378		18
Other comprehensive loss	(6,069)				(6,069)
Ending balance (in shares) at Mar. 31, 2019		61,051
Ending balance at Mar. 31, 2019	879,499	$ 611	820,788	127,513	(69,710)	297
Beginning balance (in shares) at Dec. 31, 2018		60,890
Beginning balance at Dec. 31, 2018	$ 867,015	$ 609	807,986	121,114	(62,973)	279
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase and retirement of common shares (in shares)	(81)
Repurchase and retirement of common shares	$ (6,997)
Net income	224,929
Ending balance (in shares) at Sep. 30, 2019		61,169
Ending balance at Sep. 30, 2019	1,013,222	$ 612	867,185	228,837	(83,591)	179
Beginning balance (in shares) at Mar. 31, 2019		61,051
Beginning balance at Mar. 31, 2019	879,499	$ 611	820,788	127,513	(69,710)	297
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee stock compensation (in shares)		14
Employee stock compensation	22,142		22,142
Deferred compensation	(1,881)		(1,303)	(578)
Proceeds from stock issuances under employee plans (in shares)		59
Proceeds from stock issuances under employee plans	3,006		3,006
Cash dividends declared	(37,286)			(37,286)
Repurchase and retirement of common shares (in shares)		(5)
Repurchase and retirement of common shares	(427)		(55)	(372)
Net income	88,145			88,263		(118)
Other comprehensive loss	(1,110)				(1,110)
Ending balance (in shares) at Jun. 30, 2019		61,119
Ending balance at Jun. 30, 2019	952,088	$ 611	844,578	177,540	(70,820)	179
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee stock compensation (in shares)		27
Employee stock compensation	22,326	$ 1	22,325
Deferred compensation	(1,009)		(1,599)	590
Proceeds from stock issuances under employee plans (in shares)		28
Proceeds from stock issuances under employee plans	1,952	$ 1	1,951
Cash dividends declared	(37,292)			(37,292)
Repurchase and retirement of common shares (in shares)		(5)
Repurchase and retirement of common shares	(460)	$ (1)	(70)	(389)
Net income	88,388			88,388
Other comprehensive loss	(12,771)				(12,771)
Ending balance (in shares) at Sep. 30, 2019		61,169
Ending balance at Sep. 30, 2019	$ 1,013,222	$ 612	$ 867,185	$ 228,837	$ (83,591)	$ 179