Balance Sheet Offsetting - Schedule of Assets and Liabilities Subject to an Enforceable Master Netting Arrangement or Repurchase Agreements (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Liabilities:
Repurchase Agreements, Gross Amounts of Recognized Liabilities	$ 602,106	$ 604,306
Repurchase Agreements, Gross Amounts Offset in the Statements of Condition	0	0
Repurchase Agreements, Net Amounts of Liabilities Presented in the Statements of Condition	602,106	604,306
Securities Sold under Agreements to Repurchase, Net Amount Offset Against Collateral	0	0
Repurchase Agreements, Fair Value of Collateral Pledged	602,106	604,306
Securities Sold under Agreements to Repurchase, Net Amount Offset Against Collateral	0	0
Private Institutions
Liabilities:
Repurchase Agreements, Gross Amounts of Recognized Liabilities	600,000	600,000
Repurchase Agreements, Gross Amounts Offset in the Statements of Condition	0	0
Repurchase Agreements, Net Amounts of Liabilities Presented in the Statements of Condition	600,000	600,000
Securities Sold under Agreements to Repurchase, Net Amount Offset Against Collateral	0	0
Repurchase Agreements, Fair Value of Collateral Pledged	600,000	600,000
Securities Sold under Agreements to Repurchase, Net Amount Offset Against Collateral	0	0
Government Entities
Liabilities:
Repurchase Agreements, Gross Amounts of Recognized Liabilities	2,106	4,306
Repurchase Agreements, Gross Amounts Offset in the Statements of Condition	0	0
Repurchase Agreements, Net Amounts of Liabilities Presented in the Statements of Condition	2,106	4,306
Securities Sold under Agreements to Repurchase, Net Amount Offset Against Collateral	0	0
Repurchase Agreements, Fair Value of Collateral Pledged	2,106	4,306
Securities Sold under Agreements to Repurchase, Net Amount Offset Against Collateral	0	0
Interest Rate Swap Agreements | Institutional Counterparties
Assets:
Gross Amounts of Recognized Assets	5	584
Gross Amounts Offset in the Statements of Condition	0	0
Net Amounts of Assets Presented in the Statements of Condition	5	584
Netting Adjustments per Master Netting Arrangements	5	584
Gross Amounts Not Offset in the Statements of Condition - FV of collateral pledged	0	0
Derivative Assets, Net Amount	0	0
Liabilities:
Gross Amounts of Recognized Liabilities	19,161	5,361
Gross Amounts Offset in the Statements of Condition	0	0
Net Amounts of Liabilities Presented in the Statements of Condition	19,161	5,361
Derivative Liability, Netting Adjustments per Master Netting Arrangements	5	584
Derivative, Collateral, Right to Reclaim Securities	8,962	3,818
Derivative Liabilities, Net Amount	$ 10,194	$ 959