Investment Securities - Amortized Cost and Fair Value, by Contractual Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Amortized Cost
Due after one year through five years	$ 41,497
Due after five years through ten years	83,608
Due after ten years	57,249
Total contractual maturities	182,354
Amortized Cost	6,951,153	$ 5,985,031
Fair Value
Due after one year through five years	41,787
Due after five years through ten years	82,670
Due after ten years	56,315
Total contractual maturities	180,772
Fair value	6,953,930	6,071,415
Mortgage-backed securities:
Amortized Cost
Mortgaged-backed securities and collateralized mortgage obligations	3,098,785
Fair Value
Mortgaged-backed securities and collateralized mortgage obligations	3,091,989
Residential - Government agency
Amortized Cost
Mortgaged-backed securities and collateralized mortgage obligations	110,115
Amortized Cost	110,115	155,169
Fair Value
Mortgaged-backed securities and collateralized mortgage obligations	113,289
Fair value	113,289	160,462
Residential - Government-sponsored enterprises
Amortized Cost
Mortgaged-backed securities and collateralized mortgage obligations	1,257,032
Amortized Cost	1,257,032	434,282
Fair Value
Mortgaged-backed securities and collateralized mortgage obligations	1,263,448
Fair value	1,263,448	447,200
Commercial - Government agency
Amortized Cost
Mortgaged-backed securities and collateralized mortgage obligations	487,607
Amortized Cost	487,607	583,232
Fair Value
Mortgaged-backed securities and collateralized mortgage obligations	491,447
Fair value	491,447	599,650
Commercial - Government-sponsored enterprises
Amortized Cost
Mortgaged-backed securities and collateralized mortgage obligations	1,244,031
Amortized Cost	1,244,031	931,095
Fair Value
Mortgaged-backed securities and collateralized mortgage obligations	1,223,805
Fair value	1,223,805	932,157
Collateralized mortgage obligations
Amortized Cost
Mortgaged-backed securities and collateralized mortgage obligations	3,670,014
Fair Value
Mortgaged-backed securities and collateralized mortgage obligations	3,681,169
Government agency
Amortized Cost
Mortgaged-backed securities and collateralized mortgage obligations	1,645,170
Amortized Cost	1,645,170	1,902,326
Fair Value
Mortgaged-backed securities and collateralized mortgage obligations	1,662,134
Fair value	1,662,134	1,933,553
Government-sponsored enterprises
Amortized Cost
Mortgaged-backed securities and collateralized mortgage obligations	2,024,844
Amortized Cost	2,024,844	1,808,804
Fair Value
Mortgaged-backed securities and collateralized mortgage obligations	2,019,035
Fair value	$ 2,019,035	$ 1,826,972

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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