Balance Sheet Offsetting - Remaining Contractual Maturities of Repurchase Agreements by Class of Collateral Pledged (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	$ 600,490	$ 600,590
Debt Securities Issued by States and Political Subdivisions
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	490	590
Residential - Government Agencies
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	94,469	103,809
Residential - U.S. Government-Sponsored Enterprises
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	505,531	496,191
Maturity Up To 90 Days
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	0	100
Maturity Up To 90 Days | Debt Securities Issued by States and Political Subdivisions
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	0	100
Maturity Up To 90 Days | Residential - Government Agencies
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	0	0
Maturity Up To 90 Days | Residential - U.S. Government-Sponsored Enterprises
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	0	0
Maturity 91 To 365 Days
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	0	0
Maturity 91 To 365 Days | Debt Securities Issued by States and Political Subdivisions
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	0	0
Maturity 91 To 365 Days | Residential - Government Agencies
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	0	0
Maturity 91 To 365 Days | Residential - U.S. Government-Sponsored Enterprises
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	0	0
Maturity 1 To 3 Years
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	575,000	575,000
Maturity 1 To 3 Years | Debt Securities Issued by States and Political Subdivisions
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	0	0
Maturity 1 To 3 Years | Residential - Government Agencies
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	77,117	83,599
Maturity 1 To 3 Years | Residential - U.S. Government-Sponsored Enterprises
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	497,883	491,401
Maturity After 3 Years
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	25,490	25,490
Maturity After 3 Years | Debt Securities Issued by States and Political Subdivisions
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	490	490
Maturity After 3 Years | Residential - Government Agencies
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	17,352	20,210
Maturity After 3 Years | Residential - U.S. Government-Sponsored Enterprises
Securities Sold Under Agreements to Repurchase
Securities Sold under Agreements to Repurchase	$ 7,648	$ 4,790