Fair Value Measurements on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financial Assets
Debt securities, available-for-sale	$ 2,459,036	$ 2,571,663
Recurring Measurements
Financial Assets
Loans held for sale, at fair value	100,441	33,156
Total assets measured at fair value on a recurring basis	2,559,477	2,604,819
Financial Liabilities
Total liabilities measured at fair value on a recurring basis		3,769
Interest Rate Swaps \| Recurring Measurements
Financial Liabilities
Derivatives		3,769
U.S. government and federal agency \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	147,434	23,649
U.S. government sponsored enterprises \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	67,189	120,208
State and local governments \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	613,865	852,250
Corporate bonds \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	147,383	290,817
Residential mortgage-backed securities \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	767,253	792,915
Commercial mortgage-backed securities \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	715,912	491,824
Level 1 \| Recurring Measurements
Financial Assets
Loans held for sale, at fair value	0	0
Total assets measured at fair value on a recurring basis	0	0
Financial Liabilities
Total liabilities measured at fair value on a recurring basis		0
Level 1 \| Interest Rate Swaps \| Recurring Measurements
Financial Liabilities
Derivatives		0
Level 1 \| U.S. government and federal agency \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	0	0
Level 1 \| U.S. government sponsored enterprises \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	0	0
Level 1 \| State and local governments \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	0	0
Level 1 \| Corporate bonds \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	0	0
Level 1 \| Residential mortgage-backed securities \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	0	0
Level 1 \| Commercial mortgage-backed securities \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	0	0
Level 2 \| Recurring Measurements
Financial Assets
Loans held for sale, at fair value	100,441	33,156
Total assets measured at fair value on a recurring basis	2,559,477	2,604,819
Financial Liabilities
Total liabilities measured at fair value on a recurring basis		3,769
Level 2 \| Interest Rate Swaps \| Recurring Measurements
Financial Liabilities
Derivatives		3,769
Level 2 \| U.S. government and federal agency \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	147,434	23,649
Level 2 \| U.S. government sponsored enterprises \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	67,189	120,208
Level 2 \| State and local governments \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	613,865	852,250
Level 2 \| Corporate bonds \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	147,383	290,817
Level 2 \| Residential mortgage-backed securities \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	767,253	792,915
Level 2 \| Commercial mortgage-backed securities \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	715,912	491,824
Level 3 \| Recurring Measurements
Financial Assets
Loans held for sale, at fair value	0	0
Total assets measured at fair value on a recurring basis	0	0
Financial Liabilities
Total liabilities measured at fair value on a recurring basis		0
Level 3 \| Interest Rate Swaps \| Recurring Measurements
Financial Liabilities
Derivatives		0
Level 3 \| U.S. government and federal agency \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	0	0
Level 3 \| U.S. government sponsored enterprises \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	0	0
Level 3 \| State and local governments \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	0	0
Level 3 \| Corporate bonds \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	0	0
Level 3 \| Residential mortgage-backed securities \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	0	0
Level 3 \| Commercial mortgage-backed securities \| Recurring Measurements
Financial Assets
Debt securities, available-for-sale	$ 0	$ 0

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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