Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Net income	$ 107,975	$ 95,056	$ 342,058	$ 242,881
Other comprehensive income (loss), before tax:
Change in net unrealized gain/loss on securities available for sale during the period	(80,668)	20,332	(209,779)	406,959
Change in net unrealized gain on securities transferred to held to maturity	(237)	(294)	(741)	(979)
Reclassification adjustment for net (gains) losses included in net income	0	0	0	(108,989)
Total securities available for sale and transferred securities, before tax amount	(80,905)	20,038	(210,520)	296,991
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)	1,529	1,330	4,587	3,989
Total defined-benefit post-retirement benefit plans	1,529	1,330	4,587	3,989
Other comprehensive income (loss), before tax	(79,376)	21,368	(205,933)	300,980
Deferred tax expense (benefit)	(16,669)	4,487	(43,246)	63,205
Other comprehensive income (loss), net of tax	(62,707)	16,881	(162,687)	237,775
Comprehensive income (loss)	$ 45,268	$ 111,937	$ 179,371	$ 480,656