Investment Securities (Tables)

9 Months Ended

Sep. 30, 2015

Investments, Debt and Equity Securities [Abstract]

Investment securities available for sale

September 30, 2015:	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
	($ in Thousands)
Investment securities available for sale:
U.S. Treasury securities	$	999	$	3	$	—		$	1,002
Obligations of state and political subdivisions ("municipal securities")	409,529		18,176		(4		)	427,701
Residential mortgage-related securities:
FNMA / FHLMC	1,932,740		52,232		(4,182		)	1,980,790
GNMA	1,106,601		4,106		(2,574		)	1,108,133
Private-label	1,755		1		(10		)	1,746
GNMA commercial mortgage-related securities	1,885,776		6,461		(14,656		)	1,877,581
Other securities (debt and equity)	6,640		63		—			6,703
Total investment securities available for sale	$	5,344,040	$	81,042	$	(21,426	)	$	5,403,656
Investment securities held to maturity:
Municipal securities	$	604,799	$	10,023	$	(1,450	)	$	613,372
Total investment securities held to maturity	$	604,799	$	10,023	$	(1,450	)	$	613,372
December 31, 2014:	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
	($ in Thousands)
Investment securities available for sale:
U.S. Treasury securities	$	999	$	—	$	(1	)	$	998
Municipal securities	560,839		21,869		(29		)	582,679
Residential mortgage-related securities:
FNMA / FHLMC	3,534,240		59,640		(30,423		)	3,563,457
GNMA	165,863		1,596		(127		)	167,332
Private-label	2,297		7		(10		)	2,294
GNMA commercial mortgage-related securities	1,097,913		1,922		(25,942		)	1,073,893
Other securities (debt and equity)	6,108		51		—			6,159
Total investment securities available for sale	$	5,368,259	$	85,085	$	(56,532	)	$	5,396,812
Investment securities held to maturity:
Municipal securities	$	404,455	$	9,444	$	(832	)	$	413,067
Total investment securities held to maturity	$	404,455	$	9,444	$	(832	)	$	413,067

Investment securities held to maturity

September 30, 2015:	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
	($ in Thousands)
Investment securities available for sale:
U.S. Treasury securities	$	999	$	3	$	—		$	1,002
Obligations of state and political subdivisions ("municipal securities")	409,529		18,176		(4		)	427,701
Residential mortgage-related securities:
FNMA / FHLMC	1,932,740		52,232		(4,182		)	1,980,790
GNMA	1,106,601		4,106		(2,574		)	1,108,133
Private-label	1,755		1		(10		)	1,746
GNMA commercial mortgage-related securities	1,885,776		6,461		(14,656		)	1,877,581
Other securities (debt and equity)	6,640		63		—			6,703
Total investment securities available for sale	$	5,344,040	$	81,042	$	(21,426	)	$	5,403,656
Investment securities held to maturity:
Municipal securities	$	604,799	$	10,023	$	(1,450	)	$	613,372
Total investment securities held to maturity	$	604,799	$	10,023	$	(1,450	)	$	613,372
December 31, 2014:	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
	($ in Thousands)
Investment securities available for sale:
U.S. Treasury securities	$	999	$	—	$	(1	)	$	998
Municipal securities	560,839		21,869		(29		)	582,679
Residential mortgage-related securities:
FNMA / FHLMC	3,534,240		59,640		(30,423		)	3,563,457
GNMA	165,863		1,596		(127		)	167,332
Private-label	2,297		7		(10		)	2,294
GNMA commercial mortgage-related securities	1,097,913		1,922		(25,942		)	1,073,893
Other securities (debt and equity)	6,108		51		—			6,159
Total investment securities available for sale	$	5,368,259	$	85,085	$	(56,532	)	$	5,396,812
Investment securities held to maturity:
Municipal securities	$	404,455	$	9,444	$	(832	)	$	413,067
Total investment securities held to maturity	$	404,455	$	9,444	$	(832	)	$	413,067

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

	Available for Sale					Held to Maturity
($ in Thousands)	Amortized Cost		Fair Value			Amortized Cost		Fair Value
Due in one year or less	$	39,763	$	40,025		$	—	$	—
Due after one year through five years	236,730		248,772			3,980		4,042
Due after five years through ten years	140,072		145,956			133,801		136,164
Due after ten years	585		599			467,018		473,166
Total debt securities	417,150		435,352			604,799		613,372
Residential mortgage-related securities:
FNMA / FHLMC	1,932,740		1,980,790			—		—
GNMA	1,106,601		1,108,133			—		—
Private-label	1,755		1,746			—		—
GSE commercial mortgage-related securities	1,885,776		1,877,581			—		—
Equity securities	18		54			—		—
Total investment securities	$	5,344,040	$	5,403,656		$	604,799	$	613,372
Ratio of Fair Value to Amortized Cost			101.1		%			101.4		%

Schedule of Realized Gain (Loss)

	Nine Months Ended September 30,						Year Ended December 31,
	2015			2014			2014
				($ in Thousands)
Gross gains	$	8,047		$	1,159		$	1,184
Gross losses	(4,009		)	(690		)	(690		)
Investment securities gains, net	$	4,038		$	469		$	494
Proceeds from sales of investment securities	$	1,206,242		$	101,987		$	102,011

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

	Less than 12 months						12 months or more						Total
September 30, 2015	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:
Municipal securities	2	$	(2	)	$	628	1	$	(2	)	$	186	$	(4	)	$	814
Residential mortgage-related securities:
GSE	51	(2,894		)	854,924		20	(3,862		)	374,787		(6,756		)	1,229,711
Private-label	1	—			90		3	(10		)	1,591		(10		)	1,681
GSE commercial mortgage-related securities	15	(1,411		)	526,820		20	(13,245		)	445,030		(14,656		)	971,850
Total		$	(4,307	)	$	1,382,462		$	(17,119	)	$	821,594	$	(21,426	)	$	2,204,056
Investment securities held to maturity:
Municipal securities	244	$	(1,180	)	$	112,223	20	$	(270	)	$	9,405	$	(1,450	)	$	121,628
Total		$	(1,180	)	$	112,223		$	(270	)	$	9,405	$	(1,450	)	$	121,628

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, 2014.

	Less than 12 months						12 months or more						Total
December 31, 2014	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	$	(1	)	$	998	—	$	—		$	—	$	(1	)	$	998
Municipal securities	6	(9		)	3,374		6	(20		)	2,133		(29		)	5,507
Residential mortgage-related securities:
GSE	16	(1,404		)	333,713		56	(29,146		)	1,256,533		(30,550		)	1,590,246
Private-label	1	(9		)	1,772		2	(1		)	27		(10		)	1,799
GSE commercial mortgage-related securities	9	(1,766		)	329,982		20	(24,176		)	460,425		(25,942		)	790,407
Total		$	(3,189	)	$	669,839		$	(53,343	)	$	1,719,118	$	(56,532	)	$	2,388,957
Investment securities held to maturity:
Municipal securities	74	$	(216	)	$	31,924	85	$	(616	)	$	38,915	$	(832	)	$	70,839
Total		$	(216	)	$	31,924		$	(616	)	$	38,915	$	(832	)	$	70,839