Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net income	$ 93,131	$ 80,219	$ 263,625	$ 220,542
Other comprehensive income (loss), before tax:
Change in net unrealized gain/loss on securities available for sale during the period	7,082	(95,641)	131,283	191,865
Change in net unrealized gain on securities transferred to held to maturity	(3,514)	(7,278)	(13,660)	(24,629)
Reclassification adjustment for net (gains) losses included in net income	4,867	37	4,917	(14,866)
Total securities available for sale and transferred securities, before tax amount	8,435	(102,882)	122,540	152,370
Defined-benefit post-retirement benefit plans:
Change in the net actuarial gain/loss	0	0	0	(862)
Reclassification adjustment for net amortization of actuarial gain/loss included in net income as a component of net periodic cost (benefit)	1,357	1,585	4,072	4,878
Total defined-benefit post-retirement benefit plans	1,357	1,585	4,072	4,016
Other comprehensive income (loss), before tax	9,792	(101,297)	126,612	156,386
Deferred tax expense (benefit) related to other comprehensive income	3,427	(35,453)	44,314	54,736
Other comprehensive income (loss), net of tax	6,365	(65,844)	82,298	101,650
Comprehensive income (loss)	$ 99,496	$ 14,375	$ 345,923	$ 322,192