Summary of Significant Accounting Policies - Schedule of Reclassification out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Before Tax
Unrealized holding (losses)/gains on available-for-sale-securities, before tax	$ (98,334)	$ 4,200
Other comprehensive loss before tax	(133,260)	(4,686)
Provision (Benefit)
Unrealized holding (losses)/gains on available-for-sale securities, provision (benefit)	(20,649)	882
Other comprehensive (loss)/income provision (benefit)	(27,984)	(984)
After Tax
Unrealized holding (losses)/gains on available-for-sale securities, after tax	(77,685)	3,318
Reclassification adjustments, after tax	(4,923)	(2,925)
Other comprehensive income before reclassifications	(100,353)	(777)
Other comprehensive loss net of tax	(105,276)	(3,702)
Cash Flow Hedges
Before Tax
Unrealized (losses)/gains on cash flow hedges, before tax	(28,695)	(5,184)
Other comprehensive loss before tax	(28,256)	(5,665)
Provision (Benefit)
Unrealized (losses)/gains on cash flow hedges, provision (benefit)	(6,027)	(1,089)
Other comprehensive (loss)/income provision (benefit)	(5,935)	(1,190)
After Tax
Reclassification adjustments, after tax	347	(380)
Other comprehensive income before reclassifications	(22,668)	(4,095)
Other comprehensive loss net of tax	(22,321)	(4,475)
Available-for-Sale Securities \| Accumulated Net Investment Gain (Loss) Including Portion Attributable to Noncontrolling Interest
Before Tax
Other comprehensive loss before tax	(99,316)	3,241
Provision (Benefit)
Other comprehensive (loss)/income provision (benefit)	(20,855)	681
After Tax
Reclassification adjustments, after tax	(776)	(758)
Other comprehensive income before reclassifications	(77,685)	3,318
Other comprehensive loss net of tax	(78,461)	2,560
Held-to-Maturity Securities \| Accumulated Net Investment Gain (Loss) Including Portion Attributable to Noncontrolling Interest
Before Tax
Other comprehensive loss before tax	(5,688)	(2,262)
Provision (Benefit)
Other comprehensive (loss)/income provision (benefit)	(1,194)	(475)
After Tax
Reclassification adjustments, after tax	(4,494)	(1,787)
Other comprehensive income before reclassifications	0	0
Other comprehensive loss net of tax	(4,494)	(1,787)
Net Interest Income \| Available-for-Sale Securities \| Accumulated Net Investment Gain (Loss) Including Portion Attributable to Noncontrolling Interest \| Reclassification out of Accumulated Other Comprehensive Income
Before Tax
Reclassification adjustments, before tax	(969)	(953)
Provision (Benefit)
Reclassification adjustments, provision (benefit)	(203)	(200)
After Tax
Reclassification adjustments, after tax	(766)	(753)
Net Interest Income \| Held-to-Maturity Securities \| Accumulated Net Investment Gain (Loss) Including Portion Attributable to Noncontrolling Interest \| Reclassification out of Accumulated Other Comprehensive Income
Before Tax
Reclassification adjustments, before tax	(5,688)	(2,262)
Provision (Benefit)
Reclassification adjustments, provision (benefit)	(1,194)	(475)
After Tax
Reclassification adjustments, after tax	(4,494)	(1,787)
Other Income \| Available-for-Sale Securities \| Accumulated Net Investment Gain (Loss) Including Portion Attributable to Noncontrolling Interest \| Reclassification out of Accumulated Other Comprehensive Income
Before Tax
Reclassification adjustments, before tax	(13)	(6)
Provision (Benefit)
Reclassification adjustments, provision (benefit)	(3)	(1)
After Tax
Reclassification adjustments, after tax	(10)	(5)
Interest Expense \| Cash Flow Hedges \| Reclassification out of Accumulated Other Comprehensive Income
Before Tax
Reclassification adjustments, before tax	439	(481)
Provision (Benefit)
Reclassification adjustments, provision (benefit)	92	(101)
After Tax
Reclassification adjustments, after tax	$ 347	$ (380)

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