Investment Securities, AFS and HTM Contractual Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Amortized Cost
Available for Sale, Due in one year or less	$ 2,001
Available for Sale, Due after one year through five years	2,000
Available for Sale, Due after five years through ten years	0
Available for Sale, Due after ten years	0
Available for Sale, Total debt securities	4,001
Available for Sale, amortized cost	4,191,366	$ 4,100,417
Fair Value
Available for Sale, Due in one year or less	1,997
Available for Sale, Due after one year through five years	2,000
Available for Sale, Due after five years through ten years	0
Available for Sale, Due after ten years	0
Available for Sale, Total debt securities	3,997
Investment securities available for sale, at fair value	$ 4,054,197	4,043,446
Available for Sale, Ratio of Fair Value to Amortized Cost	96.70%
Amortized Cost
Held to Maturity, Due in one year or less	$ 48,561
Held to Maturity, Due after one year through five years	188,337
Held to Maturity, Due after five years through ten years	385,908
Held to Maturity, Due after ten years	1,059,355
Held to Maturity, Total Debt Securities	1,682,162
Held to Maturity, Amortized Cost	2,661,755	2,282,853
Fair Value
Held to Maturity, Due in one year or less	48,871
Held to Maturity, Due after one year through five years	186,335
Held to Maturity, Due after five years through ten years	377,705
Held to Maturity, Due after ten years	1,037,135
Held to Maturity, Securities, Debt Securities	1,650,046
Held to Maturity, Total debt securities at fair value	$ 2,595,017	2,283,574
Held to Maturity, Ratio of Fair Value to Amortized Cost	97.50%
Private-label
Amortized Cost
Available for Sale, amortized cost	$ 1,022	1,067
Fair Value
Investment securities available for sale, at fair value	1,018	1,059
Amortized Cost
Held to Maturity, Amortized Cost	0
Fair Value
Held to Maturity, Total debt securities at fair value	0
GNMA Commercial Mortgage-Related Securities
Amortized Cost
Available for Sale, amortized cost	1,306,802	1,547,173
Fair Value
Investment securities available for sale, at fair value	1,250,978	1,513,277
Amortized Cost
Held to Maturity, Amortized Cost	516,454	546,098
Fair Value
Held to Maturity, Total debt securities at fair value	498,520	539,888
FFELP asset backed securities
Amortized Cost
Available for Sale, amortized cost	298,282	144,322
Fair Value
Investment securities available for sale, at fair value	299,947	145,176
Amortized Cost
Held to Maturity, Amortized Cost	0
Fair Value
Held to Maturity, Total debt securities at fair value	0
Equity Securities
Amortized Cost
Available for Sale, amortized cost	1,573	1,519
Fair Value
Investment securities available for sale, at fair value	1,573	1,632
Amortized Cost
Held to Maturity, Amortized Cost	0
Fair Value
Held to Maturity, Total debt securities at fair value	0
FNMA/FHLMC \| Residential Related Securities
Amortized Cost
Available for Sale, amortized cost	320,148	457,680
Fair Value
Investment securities available for sale, at fair value	316,674	464,768
Amortized Cost
Held to Maturity, Amortized Cost	95,603	40,995
Fair Value
Held to Maturity, Total debt securities at fair value	92,499	40,904
GNMA \| Residential Related Securities
Amortized Cost
Available for Sale, amortized cost	2,259,538	1,944,453
Fair Value
Investment securities available for sale, at fair value	2,180,010	1,913,350
Amortized Cost
Held to Maturity, Amortized Cost	367,536	414,440
Fair Value
Held to Maturity, Total debt securities at fair value	$ 353,952	$ 410,740

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- Definition

Fair value of investment in debt security measured at amortized cost (held-to-maturity).

+ References

+ Details

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- Details

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