CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statements of Comprehensive Income/(loss)
Net income/(loss)	$ 452,373	$ 556,507	$ 176,980
Other comprehensive income/(loss), net of tax:
Net unrealized gains/(losses) on securities available-for-sale	106,815	(48,897)	(4,765)
Net unrealized gains/(losses) on cash flow hedges	15,339	(4,142)
Net unrealized gains/(losses) on cash flow hedges			(5,101)
Net unrealized gains/(losses) on pension and other postretirement plans	14,854	(541)	(7,759)
Other comprehensive income/(loss)	137,008	(53,580)	(17,625)
Comprehensive income/(loss)	589,381	502,927	159,355
Comprehensive income attributable to noncontrolling interest	11,465	11,465	11,465
Comprehensive income attributable to controlling interest	577,916	491,462	147,890
Income tax expense/(benefit) of items included in Other comprehensive income:
Net unrealized gains/(losses) on securities available-for-sale	35,062	(16,054)	(2,955)
Net unrealized gains/(losses) on cash flow hedges	5,035	(1,360)	(3,163)
Net unrealized gains/(losses) on cash flow hedges			(3,163)
Net unrealized gains/(losses) on pension and other postretirement plans	$ 4,876	$ (177)	$ (832)