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
Statement of Comprehensive Income [Abstract]
Net Income	$ 61,607	$ 62,108	$ 127,213	$ 178,550
Other Comprehensive Income, net of tax:
Unrealized gain on securities	4,333	18,029	56,186	63,244
Amortization of net unrealized losses on available for sale securities transferred to held to maturity	928	3,430	2,517	5,425
Non-credit related unrealized loss on other-than-temporarily impaired debt securities	0	0	0	(682)
Amortization of net unrecognized pension and postretirement income	255	277	765	843
Other Comprehensive Income	5,515	18,238	57,091	65,144
Total Comprehensive Income	$ 67,122	$ 80,346	$ 184,304	$ 243,694