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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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value of financial and nonfinancial obligations.

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Amount, after valuation allowance, of financing receivable held for sale and not part of disposal group. Excludes loan covered under loss sharing agreement and loan classified as investment in debt security.

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Fair value portion of other assets.

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Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

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Fair Value of Assets and Liabilities - Balances of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Assets:
Available-for-Sale: Fair Value	$ 3,791,689	$ 2,619,003	$ 2,007,942
Loans Held for Sale	82,565	39,062
Derivatives	96,167	28,931
Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale: Fair Value	174,245	221,131	392,401
Debt Securities Issued by Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	1,062	22,147	56
Debt Securities Issued by Corporations
Assets:
Available-for-Sale: Fair Value	224,605	336,321	223,140
Residential - Government Agencies
Assets:
Available-for-Sale: Fair Value	1,594,815	1,172,826	190,442
Residential - U.S. Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	1,518,283	586,761	578,527
Commercial - Government Agencies
Assets:
Available-for-Sale: Fair Value	253,839	224,720	59,380
Mortgage-Backed Securities
Assets:
Available-for-Sale: Fair Value	3,366,937	1,984,307	$ 828,349
Fair Value, Measurements, Recurring
Assets:
Available-for-Sale: Fair Value	3,791,689	2,619,003
Loans Held for Sale	82,565	39,062
Mortgage Servicing Rights	958	1,126
Other Assets	53,410	41,464
Derivatives	96,167	28,931
Total Assets Measured at Fair Value on a Recurring Basis	4,024,789	2,729,586
Liabilities:
Derivatives	18,161	6,377
Total Liabilities Measured at Fair Value on a Recurring Basis	18,161	6,377
Fair Value, Measurements, Recurring \| Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale: Fair Value	174,245	221,131
Fair Value, Measurements, Recurring \| Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale: Fair Value	24,840	55,097
Fair Value, Measurements, Recurring \| Debt Securities Issued by Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	1,062	22,147
Fair Value, Measurements, Recurring \| Debt Securities Issued by Corporations
Assets:
Available-for-Sale: Fair Value	224,605	336,321
Fair Value, Measurements, Recurring \| Residential - Government Agencies
Assets:
Available-for-Sale: Fair Value	1,594,815	1,172,826
Fair Value, Measurements, Recurring \| Residential - U.S. Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	1,518,283	586,761
Fair Value, Measurements, Recurring \| Commercial - Government Agencies
Assets:
Available-for-Sale: Fair Value	253,839	224,720
Fair Value, Measurements, Recurring \| Mortgage-Backed Securities
Assets:
Available-for-Sale: Fair Value	3,366,937	1,984,307
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
Assets:
Available-for-Sale: Fair Value	921	1,155
Loans Held for Sale	0	0
Mortgage Servicing Rights	0	0
Other Assets	53,410	41,464
Derivatives	0	0
Total Assets Measured at Fair Value on a Recurring Basis	54,331	42,619
Liabilities:
Derivatives	0	0
Total Liabilities Measured at Fair Value on a Recurring Basis	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) \| Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale: Fair Value	921	1,155
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) \| Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) \| Debt Securities Issued by Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) \| Debt Securities Issued by Corporations
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) \| Residential - Government Agencies
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) \| Residential - U.S. Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) \| Commercial - Government Agencies
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) \| Mortgage-Backed Securities
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2)
Assets:
Available-for-Sale: Fair Value	3,790,768	2,617,848
Loans Held for Sale	82,565	39,062
Mortgage Servicing Rights	0	0
Other Assets	0	0
Derivatives	878	308
Total Assets Measured at Fair Value on a Recurring Basis	3,874,211	2,657,218
Liabilities:
Derivatives	752	327
Total Liabilities Measured at Fair Value on a Recurring Basis	752	327
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale: Fair Value	173,324	219,976
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale: Fair Value	24,840	55,097
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Debt Securities Issued by Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	1,062	22,147
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Debt Securities Issued by Corporations
Assets:
Available-for-Sale: Fair Value	224,605	336,321
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Residential - Government Agencies
Assets:
Available-for-Sale: Fair Value	1,594,815	1,172,826
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Residential - U.S. Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	1,518,283	586,761
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Commercial - Government Agencies
Assets:
Available-for-Sale: Fair Value	253,839	224,720
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Mortgage-Backed Securities
Assets:
Available-for-Sale: Fair Value	3,366,937	1,984,307
Fair Value, Measurements, Recurring \| Significant Other Unobservable Inputs (Level 3)
Assets:
Available-for-Sale: Fair Value	0	0
Loans Held for Sale	0	0
Mortgage Servicing Rights	958	1,126
Other Assets	0	0
Derivatives	95,289	28,623
Total Assets Measured at Fair Value on a Recurring Basis	96,247	29,749
Liabilities:
Derivatives	17,409	6,050
Total Liabilities Measured at Fair Value on a Recurring Basis	17,409	6,050
Fair Value, Measurements, Recurring \| Significant Other Unobservable Inputs (Level 3) \| Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Other Unobservable Inputs (Level 3) \| Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Other Unobservable Inputs (Level 3) \| Debt Securities Issued by Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Other Unobservable Inputs (Level 3) \| Debt Securities Issued by Corporations
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Other Unobservable Inputs (Level 3) \| Residential - Government Agencies
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Other Unobservable Inputs (Level 3) \| Residential - U.S. Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Other Unobservable Inputs (Level 3) \| Commercial - Government Agencies
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Other Unobservable Inputs (Level 3) \| Mortgage-Backed Securities
Assets:
Available-for-Sale: Fair Value	$ 0	$ 0