Investment Securities (Tables)

3 Months Ended

Mar. 31, 2015

Investments, Debt and Equity Securities [Abstract]

Investment securities available for sale

March 31, 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)	501,679		22,912		(4		)	524,587
Residential mortgage-related securities:
Government-sponsored enterprise (“GSE”)	3,613,144		73,227		(11,257		)	3,675,114
Private-label	1,962		1		(10		)	1,953
GSE commercial mortgage-related securities	1,158,217		6,114		(15,075		)	1,149,256
Other securities (debt and equity)	6,338		60		—			6,398
Total investment securities available for sale	$	5,282,339	$	102,317	$	(26,346	)	$	5,358,310
Investment securities held to maturity:
Obligations of state and political subdivisions (municipal securities)	$	438,047	$	9,482	$	(832	)	$	446,697
Total investment securities held to maturity	$	438,047	$	9,482	$	(832	)	$	446,697
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
Obligations of state and political subdivisions (municipal securities)	560,839		21,869		(29		)	582,679
Residential mortgage-related securities:
GSE	3,700,103		61,236		(30,550		)	3,730,789
Private-label	2,297		7		(10		)	2,294
GSE 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:
Obligations of state and political subdivisions (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

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

March 31, 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)	501,679		22,912		(4		)	524,587
Residential mortgage-related securities:
Government-sponsored enterprise (“GSE”)	3,613,144		73,227		(11,257		)	3,675,114
Private-label	1,962		1		(10		)	1,953
GSE commercial mortgage-related securities	1,158,217		6,114		(15,075		)	1,149,256
Other securities (debt and equity)	6,338		60		—			6,398
Total investment securities available for sale	$	5,282,339	$	102,317	$	(26,346	)	$	5,358,310
Investment securities held to maturity:
Obligations of state and political subdivisions (municipal securities)	$	438,047	$	9,482	$	(832	)	$	446,697
Total investment securities held to maturity	$	438,047	$	9,482	$	(832	)	$	446,697
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
Obligations of state and political subdivisions (municipal securities)	560,839		21,869		(29		)	582,679
Residential mortgage-related securities:
GSE	3,700,103		61,236		(30,550		)	3,730,789
Private-label	2,297		7		(10		)	2,294
GSE 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:
Obligations of state and political subdivisions (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	$	40,879	$	41,115		$	—	$	—
Due after one year through five years	233,433		245,483			2,253		2,291
Due after five years through ten years	234,102		244,730			122,372		124,896
Due after ten years	584		609			313,422		319,510
Total debt securities	508,998		531,937			438,047		446,697
Residential mortgage-related securities:
GSE	3,613,144		3,675,114			—		—
Private-label	1,962		1,953			—		—
GSE commercial mortgage-related securities	1,158,217		1,149,256			—		—
Equity securities	18		50			—		—
Total investment securities	$	5,282,339	$	5,358,310		$	438,047	$	446,697
Ratio of Fair Value to Amortized Cost			101.4		%			102.0		%

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
March 31, 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:
Obligations of state and political subdivisions (municipal securities)	2	$	(1	)	$	629	1	$	(3	)	$	186	$	(4	)	$	815
Residential mortgage-related securities:
GSE	22	(805		)	204,345		43	(10,452		)	1,060,452		(11,257		)	1,264,797
Private-label	1	(9		)	1,750		2	(1		)	24		(10		)	1,774
GSE commercial mortgage-related securities	4	(95		)	99,052		20	(14,980		)	455,874		(15,075		)	554,926
Total		$	(910	)	$	305,776		$	(25,436	)	$	1,516,536	$	(26,346	)	$	1,822,312
Investment securities held to maturity:
Obligations of state and political subdivisions (municipal securities)	163	$	(568	)	$	73,163	21	$	(264	)	$	9,552	$	(832	)	$	82,715
Total		$	(568	)	$	73,163		$	(264	)	$	9,552	$	(832	)	$	82,715

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
Obligations of state and political subdivisions (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:
Obligations of state and political subdivisions (municipal securities)	74	$	(216	)	$	31,924	85	$	(616	)	$	38,915	$	(832	)	$	70,839
Total		$	(216	)	$	31,924		$	(616	)	$	38,915	$	(832	)	$	70,839