Condensed Consolidated Statements of Comprehensive Income (Unaudited) - 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	$ 69,281	$ 93,865	$ 160,577	$ 292,250
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Investment securities available-for-sale	11,766	24,304	57,991	86,272
Derivative instruments	(1,912)	3,603	27,921	3,985
Defined benefit pension and other postretirement benefit plans	738	1,049	2,197	3,161
Other comprehensive income, net of tax	10,592	28,956	88,109	93,418
Comprehensive Income (Loss), Net of Tax, Attributable to Parent, Total	$ 79,873	$ 122,821	$ 248,686	$ 385,668