Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Net income	$ 118,068	$ 93,072	$ 234,083	$ 147,825
Other comprehensive income (loss), before tax:
Change in net unrealized gain/loss on securities available for sale during the period	30,668	156,509	(129,111)	386,627
Change in net unrealized gain on securities transferred to held to maturity	(245)	(308)	(504)	(685)
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	30,423	156,201	(129,615)	276,953
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	1,329	3,058	2,659
Total defined-benefit post-retirement benefit plans	1,529	1,329	3,058	2,659
Other comprehensive income (loss), before tax	31,952	157,530	(126,557)	279,612
Deferred tax expense (benefit)	6,710	33,081	(26,577)	58,718
Other comprehensive income (loss), net of tax	25,242	124,449	(99,980)	220,894
Comprehensive income (loss)	$ 143,310	$ 217,521	$ 134,103	$ 368,719