Investment Securities (Tables)

9 Months Ended

Sep. 30, 2016

Investments, Debt and Equity Securities [Abstract]

Investment securities available for sale

The amortized cost and fair values of securities available for sale and held to maturity were as follows.

September 30, 2016	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	($ in Thousands)
Investment securities available for sale:
U. S. Treasury securities	$	1,000	$	1	$	—		$	1,001
Residential mortgage-related securities:
FNMA / FHLMC	882,951		29,941		(32		)	912,860
GNMA	1,798,096		14,183		(750		)	1,811,529
Private-label	1,215		—		(15		)	1,200
GNMA commercial mortgage-related securities	2,121,913		4,218		(11,462		)	2,114,669
Other securities (debt and equity)	4,718		111		—			4,829
Total investment securities available for sale	$	4,809,893	$	48,454	$	(12,259	)	$	4,846,088
Investment securities held to maturity:
Obligations of state and political subdivisions (municipal securities)	$	1,129,056	$	31,897	$	(233	)	$	1,160,720
Residential mortgage-related securities:
FNMA / FHLMC	38,297		1,009		(16		)	39,290
GNMA	86,141		1,703		(24		)	87,820
Total investment securities held to maturity	$	1,253,494	$	34,609	$	(273	)	$	1,287,830

December 31, 2015	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	($ in Thousands)
Investment securities available for sale:
U. S. Treasury securities	$	999	$	—	$	(2	)	$	997
Residential mortgage-related securities:
FNMA / FHLMC	1,388,995		33,791		(8,160		)	1,414,626
GNMA	1,605,956		507		(16,460		)	1,590,003
Private-label	1,722		1		(14		)	1,709
GNMA commercial mortgage-related securities	1,982,477		1,334		(28,501		)	1,955,310
Other securities (debt and equity)	4,718		51		—			4,769
Total investment securities available for sale	$	4,984,867	$	35,684	$	(53,137	)	$	4,967,414
Investment securities held to maturity:
Municipal securities	$	1,043,767	$	16,803	$	(339	)	$	1,060,231
Residential mortgage-related securities:
FNMA / FHLMC	41,469		513		(645		)	41,337
GNMA	82,994		189		(309		)	82,874
Total investment securities held to maturity	$	1,168,230	$	17,505	$	(1,293	)	$	1,184,442

Investment securities held to maturity

The amortized cost and fair values of securities available for sale and held to maturity were as follows.

September 30, 2016	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	($ in Thousands)
Investment securities available for sale:
U. S. Treasury securities	$	1,000	$	1	$	—		$	1,001
Residential mortgage-related securities:
FNMA / FHLMC	882,951		29,941		(32		)	912,860
GNMA	1,798,096		14,183		(750		)	1,811,529
Private-label	1,215		—		(15		)	1,200
GNMA commercial mortgage-related securities	2,121,913		4,218		(11,462		)	2,114,669
Other securities (debt and equity)	4,718		111		—			4,829
Total investment securities available for sale	$	4,809,893	$	48,454	$	(12,259	)	$	4,846,088
Investment securities held to maturity:
Obligations of state and political subdivisions (municipal securities)	$	1,129,056	$	31,897	$	(233	)	$	1,160,720
Residential mortgage-related securities:
FNMA / FHLMC	38,297		1,009		(16		)	39,290
GNMA	86,141		1,703		(24		)	87,820
Total investment securities held to maturity	$	1,253,494	$	34,609	$	(273	)	$	1,287,830

December 31, 2015	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	($ in Thousands)
Investment securities available for sale:
U. S. Treasury securities	$	999	$	—	$	(2	)	$	997
Residential mortgage-related securities:
FNMA / FHLMC	1,388,995		33,791		(8,160		)	1,414,626
GNMA	1,605,956		507		(16,460		)	1,590,003
Private-label	1,722		1		(14		)	1,709
GNMA commercial mortgage-related securities	1,982,477		1,334		(28,501		)	1,955,310
Other securities (debt and equity)	4,718		51		—			4,769
Total investment securities available for sale	$	4,984,867	$	35,684	$	(53,137	)	$	4,967,414
Investment securities held to maturity:
Municipal securities	$	1,043,767	$	16,803	$	(339	)	$	1,060,231
Residential mortgage-related securities:
FNMA / FHLMC	41,469		513		(645		)	41,337
GNMA	82,994		189		(309		)	82,874
Total investment securities held to maturity	$	1,168,230	$	17,505	$	(1,293	)	$	1,184,442

Amortized cost and fair values of investment securities available for sale by contractual maturity

The amortized cost and fair values of investment securities available for sale and held to maturity at September 30, 2016, are shown below. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.

	Available for Sale					Held to Maturity
($ in Thousands)	Amortized Cost		Fair Value			Amortized Cost		Fair Value
Due in one year or less	$	4,500	$	4,535		$	38,786	$	27,004
Due after one year through five years	1,200		1,200			250,221		260,817
Due after five years through ten years	—		—			234,104		243,746
Due after ten years	—		—			605,945		629,153
Total debt securities	5,700		5,735			1,129,056		1,160,720
Residential mortgage-related securities:
FNMA / FHLMC	882,951		912,860			38,297		39,290
GNMA	1,798,096		1,811,529			86,141		87,820
Private-label	1,215		1,200			—		—
GNMA commercial mortgage-related securities	2,121,913		2,114,669			—		—
Equity securities	18		95			—		—
Total investment securities	$	4,809,893	$	4,846,088		$	1,253,494	$	1,287,830
Ratio of Fair Value to Amortized Cost			100.8		%			102.7		%

Realized gains and losses and proceeds from sale

During the first nine months of 2016, the Corporation sold approximately $360 million of FNMA and FHLMC mortgage-related securities and reinvested into GNMA mortgage-related securities, generating a $6 million net gain on sale. This sale of FNMA and FHLMC mortgage-related securities and the subsequent purchase of GNMA mortgage-related securities lowered risk weighted assets and related capital requirements.

	Nine Months Ended September 30,
	2016			2015
	($ in Thousands)
Gross gains	$	6,403		$	8,047
Gross losses	(202		)	(4,009		)
Investment securities gains, net	$	6,201		$	4,038
Proceeds from sales of investment securities	$	359,591		$	1,206,242

Unrealized losses and fair value of available for sale and held to maturity securities, by investment category and time length

The following represents gross unrealized losses and the related fair value of investment securities available for sale and held to maturity, aggregated by investment category and length of time individual securities have been in a continuous unrealized loss position, at September 30, 2016.

	Less than 12 months						12 months or more						Total
	Number of Securities	Unrealized Losses			Fair Value		Number of Securities	Unrealized Losses			Fair Value		Unrealized Losses			Fair Value
	($ in Thousands)
Investment securities available for sale:
Residential mortgage-related securities:
FNMA / FHLMC	3	$	(32	)	$	14,694	—	$	—		$	—	$	(32	)	$	14,694
GNMA	8	(750		)	280,378		—	—			—		(750		)	280,378
Private-label	—	—			—		1	(15		)	1,197		(15		)	1,197
GNMA commercial mortgage-related securities	40	(2,035		)	828,434		21	(9,427		)	466,898		(11,462		)	1,295,332
Total	51	$	(2,817	)	$	1,123,506	22	$	(9,442	)	$	468,095	$	(12,259	)	$	1,591,601
Investment securities held to maturity:
Municipal securities	37	$	(224	)	$	37,317	4	$	(9	)	$	1,842	$	(233	)	$	39,159
Residential mortgage-related securities:
FNMA / FHLMC	1	(8		)	1,108		1	(8		)	6,834		(16		)	7,942
GNMA	5	(24		)	6,317		—	—			—		(24		)	6,317
Total	43	$	(256	)	$	44,742	5	$	(17	)	$	8,676	$	(273	)	$	53,418

For comparative purposes, the following represents gross unrealized losses and the related fair value of investment securities available for sale and held to maturity, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at December 31, 2015.

	Less than 12 months						12 months or more						Total
	Number of Securities	Unrealized Losses			Fair Value		Number of Securities	Unrealized Losses			Fair Value		Unrealized Losses			Fair Value
	($ in Thousands)
Investment securities available for sale:
U.S. Treasury securities	1	$	(2	)	$	997	—	$	—		$	—	$	(2	)	$	997
Residential mortgage-related securities:
FNMA / FHLMC	17	(1,548		)	220,852		14	(6,612		)	338,186		(8,160		)	559,038
GNMA	46	(16,460		)	1,434,484		—	—			—		(16,460		)	1,434,484
Private-label	1	(1		)	83		3	(13		)	1,565		(14		)	1,648
GNMA commercial mortgage-related securities	40	(9,610		)	1,132,844		21	(18,891		)	448,218		(28,501		)	1,581,062
Total	105	$	(27,621	)	$	2,789,260	38	$	(25,516	)	$	787,969	$	(53,137	)	$	3,577,229
Investment securities held to maturity:
Municipal securities	53	$	(146	)	$	23,137	24	$	(193	)	$	9,254	$	(339	)	$	32,391
Residential mortgage-related securities:
FNMA / FHLMC	10	(177		)	12,754		3	(468		)	11,106		(645		)	23,860
GNMA	21	(201		)	45,499		3	(108		)	6,797		(309		)	52,296
Total	84	$	(524	)	$	81,390	30	$	(769	)	$	27,157	$	(1,293	)	$	108,547