Derivatives and Balance Sheet Offsetting Balance Sheet Offsetting (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Balance Sheet Offsetting [Line Items]
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	$ 2,100		$ 2,100
Document Period End Date			Jun. 30, 2019
Unrealized Gain (Loss) on Interest Rate Cash Flow Hedges, Pretax, Accumulated Other Comprehensive Income (Loss)	9,423	$ 0	$ 15,691	$ 0
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement	50,226		50,226
Repurchase agreements, amounts offset in balance sheet	0		0		$ 0
Repurchase agreements, net amount presented in statement of financial position	50,226		50,226		61,094
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Securities	(50,226)		(50,226)		(61,094)
Securities sold under agreements to repurchase, amount not offset	0		0		0
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	0	$ 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	17,857		17,857		7,033
Derivative, Collateral, Obligation to Return Cash	0		0		0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	17,857		17,857		7,033
Derivative Liability, Gross Amounts Offset in Balance Sheets	0		0		0
Derivative Liability	17,858		17,858		7,033
Derivative, Collateral, Right to Reclaim Cash	17,858		17,858		3,235
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	0		0		3,798
Interest rate collar [Domain]
Balance Sheet Offsetting [Line Items]
Derivative Assets, Gross Amounts Offset in the Balance Sheets	0		0
Derivative Asset	15,691		15,691
Derivative, Collateral, Obligation to Return Cash	(15,691)		(15,691)
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	0		0
Available-for-sale Securities [Member]
Balance Sheet Offsetting [Line Items]
Securities Sold under Agreements to Repurchase, Gross	50,226		50,226		61,094
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Other Assets [Member]
Balance Sheet Offsetting [Line Items]
Fair value of asset derivative instruments	17,857		17,857		7,033
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Other Liabilities [Member]
Balance Sheet Offsetting [Line Items]
Fair value of liability derivative instruments	17,858		17,858		7,033
Designated as Hedging Instrument [Member] | Interest rate collar [Domain] | Other Assets [Member]
Balance Sheet Offsetting [Line Items]
Fair value of asset derivative instruments	15,691		15,691		0
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	50,226		50,226
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	$ 50,226		$ 50,226