Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net income	$ 95,056	$ 111,836	$ 242,881	$ 339,918
Other comprehensive income (loss), before tax:
Change in net unrealized gain/loss on securities available for sale during the period	20,332	107,786	406,959	464,072
Change in net unrealized gain on securities transferred to held to maturity	(294)	(305)	(979)	(957)
Reclassification adjustment for net (gains) losses included in net income	0	(97)	(108,989)	(266)
Total securities available for sale and transferred securities, before tax amount	20,038	107,384	296,991	462,849
Defined-benefit post-retirement benefit plans:
Reclassification adjustment for net amortization of actuarial gain/loss included in net income as a component of net periodic cost (benefit)	1,330	1,406	3,989	4,218
Total defined-benefit post-retirement benefit plans	1,330	1,406	3,989	4,218
Other comprehensive income (loss), before tax	21,368	108,790	300,980	467,067
Deferred tax expense (benefit)	4,487	22,845	63,205	98,084
Other comprehensive income (loss), net of tax	16,881	85,945	237,775	368,983
Comprehensive income (loss)	$ 111,937	$ 197,781	$ 480,656	$ 708,901