Consolidated Statement of Shareholders' Equity - 6 months ended Jun. 30, 2016 - USD ($)	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	$ 4,397,691,000		$ 1,228,000	$ 4,405,775,000	$ 13,907,000	$ (51,047,000)	$ 27,828,000
Shares outstanding, beginning balance (shares) at Dec. 31, 2015		121,413,727
Stockholders' Equity Disclosure [Rollforward]
Net earnings	172,624,000				172,624,000
Other comprehensive loss-net unrealized loss on securities available-for-sale, net of tax	53,916,000		0	0	0	0	53,916,000
Restricted stock awarded and earned compensation, net of shares forfeited (shares)		526,013
Restricted stock awarded and earned stock compensation, net of shares forfeited	11,600,000		5,000	11,595,000	0	0	0
Restricted stock surrendered (shares)		(119,891)
Restricted stock surrendered	(4,416,000)		0	0	0	(4,416,000)	0
tax effect from vesting of restricted stock	3,683,000		0	3,683,000	0	0	0
Cash dividends paid	(121,794,000)		0	(121,794,000)	0	0	0
Balance, June 30, 2016 at Jun. 30, 2016	$ 4,513,304,000		$ 1,233,000	$ 4,299,259,000	$ 186,531,000	$ (55,463,000)	$ 81,744,000
Shares outstanding, ending balance (shares) at Jun. 30, 2016		121,819,849