Derivatives and Balance Sheet Offsetting Balance Sheet Offsetting (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Balance Sheet Offsetting [Line Items]
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	$ 10,600		$ 10,600
Unrealized Gain (Loss) on Interest Rate Cash Flow Hedges, Pretax, Accumulated Other Comprehensive Income (Loss)	3,402	$ 9,423	26,825	$ 15,691
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	2,190	$ 0	3,130	0
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement	51,479		51,479
Repurchase agreements, amounts offset in balance sheet	0		0		$ 0
Repurchase agreements, net amount presented in statement of financial position	51,479		51,479		64,437
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Securities	(51,479)		(51,479)		(64,437)
Securities sold under agreements to repurchase, amount not offset	0		0		0
Interest Rate Contracts [Member]
Balance Sheet Offsetting [Line Items]
Derivative Assets, Gross Amounts Offset in the Balance Sheets	0		0		0
Derivative Asset	54,424		54,424		19,144
Derivative, Collateral, Obligation to Return Cash	0		0		0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	54,424		54,424		19,144
Derivative Liability, Gross Amounts Offset in Balance Sheets	0		0		0
Derivative Liability	54,898		54,898		19,145
Derivative, Collateral, Right to Reclaim Cash	53,320		53,320		19,145
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	1,578		1,578		0
Interest rate collar [Domain]
Balance Sheet Offsetting [Line Items]
Derivative Assets, Gross Amounts Offset in the Balance Sheets	0		0		0
Derivative Asset	38,421		38,421		14,727
Derivative, Collateral, Obligation to Return Cash	(38,421)		(38,421)		(14,727)
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	0		0		0
Available-for-sale Securities [Member]
Balance Sheet Offsetting [Line Items]
Securities Sold under Agreements to Repurchase, Gross	51,479		51,479		64,437
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Balance Sheet Offsetting [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(473)		(473)	$ (2)
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Other Assets [Member]
Balance Sheet Offsetting [Line Items]
Fair value of asset derivative instruments	54,424		54,424		19,144
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Other Liabilities [Member]
Balance Sheet Offsetting [Line Items]
Fair value of liability derivative instruments	54,898		54,898		19,145
Designated as Hedging Instrument [Member] | Interest rate collar [Domain] | Other Assets [Member]
Balance Sheet Offsetting [Line Items]
Fair value of asset derivative instruments	38,421		38,421		14,727
Designated as Hedging Instrument [Member] | Interest rate collar [Domain] | Other Liabilities [Member]
Balance Sheet Offsetting [Line Items]
Fair value of liability derivative instruments	0		0		$ 0
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member]
Balance Sheet Offsetting [Line Items]
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement	51,479		51,479
Maturity Overnight [Member] | U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member]
Balance Sheet Offsetting [Line Items]
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement	$ 51,479		$ 51,479