Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Net income	$ 93,072	$ 111,586	$ 147,825	$ 228,082
Other comprehensive income (loss), before tax:
Change in net unrealized gain/loss on securities available for sale during the period	156,509	158,140	386,627	356,286
Change in net unrealized gain on securities transferred to held to maturity	(308)	(308)	(685)	(652)
Reclassification adjustment for net (gains) losses included in net income	0	(169)	(108,989)	(169)
Total securities available for sale and transferred securities, before tax amount	156,201	157,663	276,953	355,465
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)	1,329	1,406	2,659	2,812
Total defined-benefit post-retirement benefit plans	1,329	1,406	2,659	2,812
Other comprehensive income (loss), before tax	157,530	159,069	279,612	358,277
Deferred tax expense (benefit)	33,081	33,405	58,718	75,239
Other comprehensive income (loss), net of tax	124,449	125,664	220,894	283,038
Comprehensive income (loss)	$ 217,521	$ 237,250	$ 368,719	$ 511,120