Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 53,097	$ 98,649	$ 91,296	$ 198,385
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Investment securities available-for-sale	61,914	34,409	46,225	61,968
Derivative instruments	3,601	186	29,833	382
Defined benefit pension and other postretirement benefit plans	730	1,056	1,459	2,112
Other comprehensive income, net of tax	66,245	35,651	77,517	64,462
Comprehensive Income (Loss), Net of Tax, Attributable to Parent, Total	$ 119,342	$ 134,300	$ 168,813	$ 262,847