Condensed Consolidated Statement of Shareholders' Equity - 9 months ended Sep. 30, 2016 - USD ($) $ in Thousands	Total	Shares Of Common Stock [Member]	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
Balance, December 31, 2015 at Dec. 31, 2015	$ 4,397,691		$ 1,228	$ 4,405,775	$ 13,907	$ (51,047)	$ 27,828
Shares outstanding, beginning balance (shares) at Dec. 31, 2015		121,413,727
Stockholders' Equity Disclosure [Rollforward]
Net earnings	266,519				266,519
Other comprehensive loss-net unrealized loss on securities available-for-sale, net of tax	44,245						44,245
Restricted stock awarded and earned compensation, net of shares forfeited (shares)		528,392
Restricted stock awarded and earned stock compensation, net of shares forfeited	17,275		5	17,270
Restricted stock surrendered (shares)		(124,595)
Restricted stock surrendered	(4,611)					(4,611)
tax effect from vesting of restricted stock	4,226			4,226
Cash dividends paid	(182,750)			(182,750)
Balance, September 30, 2016 at Sep. 30, 2016	$ 4,542,595		$ 1,233	$ 4,244,521	$ 280,426	$ (55,658)	$ 72,073
Shares outstanding, ending balance (shares) at Sep. 30, 2016		121,817,524