Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands		Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Previously Reported [Member]	Previously Reported [Member] Retained Earnings	Restatement Adjustment [Member]
Balance, shares at Dec. 31, 2015			220,171,091
Balance, value at Dec. 31, 2015		$ 3,810,493	$ 3,520,591	$ 292,460	$ (2,558)	$ 3,849,334	$ 331,301
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		230,068		230,068		232,940		$ (2,872)
Other comprehensive loss, net of tax		(18,785)			(18,785)
Stock-based compensation		9,790	$ 9,790
Stock repurchased and retired, shares			(1,117,061)
Stock repurchased and retired		(17,708)	$ (17,708)
Issuances of common stock under stock plans, shares			1,123,000
Issuances of common stock under stock plans		2,626	$ 2,626
Cash dividends on common stock		(141,402)		(141,402)
Balance, shares at Dec. 31, 2016			220,177,030
Balance, value at Dec. 31, 2016		3,875,082	$ 3,515,299	381,126	(21,343)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		242,313		242,313		$ 246,019		$ (3,706)
Other comprehensive loss, net of tax		781			781
Stock-based compensation		9,612	$ 9,612
Stock repurchased and retired, shares			(468,555)
Stock repurchased and retired		(8,614)	$ (8,614)
Issuances of common stock under stock plans, shares			440,349
Issuances of common stock under stock plans		961	$ 961
Cash dividends on common stock		(150,768)		(150,768)
Tax rate effect reclassification	[1]	$ 0		4,430	(4,430)
Balance, shares at Dec. 31, 2017		220,148,824	220,148,824
Balance, value at Dec. 31, 2017		$ 3,969,367	$ 3,517,258	477,101	(24,992)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		316,263		316,263
Other comprehensive loss, net of tax		(43,632)			(43,632)
Stock-based compensation		7,513	$ 7,513
Stock repurchased and retired, shares			(557,648)
Stock repurchased and retired		(12,962)	$ (12,962)
Issuances of common stock under stock plans, shares			663,863
Issuances of common stock under stock plans		1,065	$ 1,065
Cash dividends on common stock		$ (181,172)		(181,172)
Balance, shares at Dec. 31, 2018		220,255,039	220,255,039
Balance, value at Dec. 31, 2018		$ 4,056,442	$ 3,512,874	$ 602,482	$ (58,914)

[1] The reclassification adjustment from accumulated other comprehensive income (loss) to retained earnings relating to the effects from the application of the Tax Cuts and Jobs Act of 2017.