Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net income	$ 111,836	$ 117,844	$ 339,918	$ 335,665
Other comprehensive income (loss), before tax:
Change in net unrealized gain/loss on securities available for sale during the period	107,786	(96,147)	464,072	(286,935)
Change in net unrealized gain on securities transferred to held to maturity	(305)	(3,764)	(957)	(8,424)
Reclassification adjustment for net (gains) losses included in net income	(97)	34	(266)	113
Total securities available for sale and transferred securities, before tax amount	107,384	(99,877)	462,849	(295,246)
Defined-benefit post-retirement benefit plans:
Change in the net actuarial gain/loss	0	0	0	0
Reclassification adjustment for net amortization of actuarial gain/loss included in net income as a component of net periodic cost (benefit)	1,406	1,250	4,218	3,751
Total defined-benefit post-retirement benefit plans	1,406	1,250	4,218	3,751
Other comprehensive income (loss), before tax	108,790	(98,627)	467,067	(291,495)
Deferred tax expense (benefit) related to other comprehensive income	22,845	(20,711)	98,084	(61,213)
Other comprehensive income (loss), net of tax	85,945	(77,916)	368,983	(230,282)
Comprehensive income (loss)	$ 197,781	$ 39,928	$ 708,901	$ 105,383