Other Comprehensive Income - Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Pre Tax Amount
Net change	$ (35,001)	$ (11,742)	$ (113,821)	$ 63,784
Tax Benefit (Expense)
Net change	8,173	2,979	26,512	(16,234)
After Tax Amount
Change in fair value			(70,177)	56,074
Less: Amounts reclassified from accumulated other comprehensive income			17,132	8,524
Total other comprehensive (loss) income	(26,828)	(8,763)	(87,309)	47,550
Amortization of gains from terminated interest rate swaps			(24,344)	(7,409)
Total realized gain, net of tax	41,200	41,200	41,200	41,200
Balance of gain after amortization, net of tax	12,300	35,900	12,300	35,900
Unrealized Gains and (Losses) on Available for Sale Securities
Pre Tax Amount
Change in fair value	(27,741)	(5,563)	(90,088)	28,750
Other comprehensive loss before reclassifications	1	0	1,166	285
Net change	(27,742)	(5,563)	(91,254)	28,465
Tax Benefit (Expense)
Change in fair value	6,132	1,242	19,911	(6,370)
Less: amortization	0	0	(257)	(63)
Net change	6,132	1,242	20,168	(6,307)
After Tax Amount
Change in fair value	(21,609)	(4,321)	(70,177)	22,380
Less: Amounts reclassified from accumulated other comprehensive income	1	0	909	222
Total other comprehensive (loss) income	(21,610)	(4,321)	(71,086)	22,158
Unrealized Gains and (Losses) on Cash Flow Hedges
Pre Tax Amount
Change in fair value	0	(142)	0	46,869
Other comprehensive loss before reclassifications	7,851	8,405	24,344	18,651
Net change	(7,851)	(8,547)	(24,344)	28,218
Tax Benefit (Expense)
Change in fair value	0	40	0	(13,175)
Less: amortization	(2,207)	(2,363)	(6,843)	(5,243)
Net change	2,207	2,403	6,843	(7,932)
After Tax Amount
Change in fair value	0	(102)	0	33,694
Less: Amounts reclassified from accumulated other comprehensive income	5,644	6,042	17,501	13,408
Total other comprehensive (loss) income	(5,644)	(6,144)	(17,501)	20,286
Defined benefit pension plans
Pre Tax Amount
Net change	592	2,368	1,777	7,101
Tax Benefit (Expense)
Net change	(166)	(666)	(499)	(1,995)
After Tax Amount
Total other comprehensive (loss) income	426	1,702	1,278	5,106
Defined Benefit Pension Plans
Pre Tax Amount
Change in fair value	0	0	0	0
Tax Benefit (Expense)
Change in fair value	0	0	0	0
After Tax Amount
Change in fair value	0	0	0	0
Less: Amounts reclassified from accumulated other comprehensive income			(1,278)	(5,106)
Defined benefit pension plans, actuarial loss
Pre Tax Amount
Other comprehensive loss before reclassifications	(3,537)	(2,361)	(10,612)	(7,082)
Tax Benefit (Expense)
Less: amortization	994	664	2,983	1,990
After Tax Amount
Less: Amounts reclassified from accumulated other comprehensive income	(2,543)	(1,697)	(7,629)	(5,092)
Defined benefit pension plans, prior service cost
Pre Tax Amount
Other comprehensive loss before reclassifications	2,945	(7)	8,835	(19)
Tax Benefit (Expense)
Less: amortization	(828)	2	(2,484)	5
After Tax Amount
Less: Amounts reclassified from accumulated other comprehensive income	$ 2,117	(5)	$ 6,351	(14)
Interest rate swaps
After Tax Amount
Amortization of gains from terminated interest rate swaps		$ 5,100		$ 5,300