Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net income	$ 85,553	$ 71,507	$ 170,494	$ 140,323
Other comprehensive income (loss), before tax:
Change in net unrealized gain/loss on securities available for sale during the period	90,390	165,288	124,201	287,506
Change in net unrealized gain on securities transferred to held to maturity	(3,860)	(9,185)	(10,146)	(17,351)
Reclassification adjustment for net (gains) losses included in net income	50	0	50	(14,903)
Total securities available for sale and transferred securities, before tax amount	86,580	156,103	114,105	255,252
Defined-benefit post-retirement benefit plans:
Change in the net actuarial gain/loss	0	(862)	0	(862)
Reclassification adjustment for net amortization of actuarial gain/loss included in net income as a component of net periodic cost (benefit)	1,358	1,740	2,715	3,293
Total defined-benefit post-retirement benefit plans	1,358	878	2,715	2,431
Other comprehensive income (loss), before tax	87,938	156,981	116,820	257,683
Deferred tax expense (benefit) related to other comprehensive income	30,778	54,943	40,887	90,189
Other comprehensive income (loss), net of tax	57,160	102,038	75,933	167,494
Comprehensive income (loss)	$ 142,713	$ 173,545	$ 246,427	$ 307,817