Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 93,865	$ 99,673	$ 292,250	$ 261,580
Other comprehensive income (loss), net of tax:
Investment securities available-for-sale	24,304	(13,811)	86,272	(50,481)
Derivative instruments	3,603	1,635	3,985	5,837
Defined benefit pension and other postretirement benefit plans	1,049	2,548	3,161	4,611
Other comprehensive income (loss), net of tax	28,956	(9,628)	93,418	(40,033)
Comprehensive income	$ 122,821	$ 90,045	$ 385,668	$ 221,547

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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