Derivatives and Balance Sheet Offsetting Balance Sheet Offsetting (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Balance Sheet Offsetting [Line Items]
Document Period End Date	Mar. 31, 2019
Unrealized Gain (Loss) on Interest Rate Cash Flow Hedges, Pretax, Accumulated Other Comprehensive Income (Loss)	$ 6,268	$ 0
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement	23,018
Repurchase agreements, amounts offset in balance sheet	0		$ 0
Repurchase agreements, net amount presented in statement of financial position	23,018		61,094
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Securities	(23,018)		(61,094)
Securities sold under agreements to repurchase, amount not offset	0		0
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	0	$ 0
Interest Rate Contracts [Member]
Balance Sheet Offsetting [Line Items]
Derivative Assets, Gross Amounts Offset in the Balance Sheets	0		0
Derivative Asset	8,815		7,033
Derivative, Collateral, Obligation to Return Securities	0		0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	8,815		7,033
Derivative Liability, Gross Amounts Offset in Balance Sheets	0		0
Derivative Liability	8,815		7,033
Derivative, Collateral, Right to Reclaim Securities	(5,573)		(3,235)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	3,242		3,798
Interest rate collar [Domain]
Balance Sheet Offsetting [Line Items]
Derivative Assets, Gross Amounts Offset in the Balance Sheets	0
Derivative Asset	6,268
Derivative, Collateral, Obligation to Return Securities	0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	6,268
Available-for-sale Securities [Member]
Balance Sheet Offsetting [Line Items]
Securities Sold under Agreements to Repurchase, Gross	23,018		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	8,815		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	8,815		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	6,268		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
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	23,018
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	$ 23,018

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