Securities (Tables)

3 Months Ended

Mar. 31, 2016

Gain (Loss) on Investments [Line Items]

Amortized Cost and Fair Value of Securities Available for Sale

Securities Available for Sale
(in thousands)	March 31, 2016								December 31, 2015
			Gross		Gross						Gross		Gross
	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
US Treasury and government agency securities	$	125	$	—	$	—	$	125	$	135	$	—	$	1	$	134
Municipal obligations		87,190		792		43		87,939		39,410		235		38		39,607
Mortgage-backed securities		1,735,836		30,862		724		1,765,974		1,750,168		19,387		11,182		1,758,373
Collateralized mortgage obligations		287,171		2,414		419		289,166		291,085		140		2,192		289,033
Corporate debt securities		3,500		—		—		3,500		3,500		—		—		3,500
Equity securities		2,449		340		27		2,762		2,447		358		48		2,757
	$	2,116,271	$	34,408	$	1,213	$	2,149,466	$	2,086,745	$	20,120	$	13,461	$	2,093,404

Amortized Cost and Fair Value of Securities Held to Maturity

Securities Held to Maturity
(in thousands)	March 31, 2016								December 31, 2015
			Gross		Gross						Gross		Gross
	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
US Treasury and government agency securities	$	50,000	$	672	$	—	$	50,672	$	50,000	$	—	$	410	$	49,590
Municipal obligations		417,911		6,270		430		423,751		185,890		3,475		1,166		188,199
Mortgage-backed securities		983,146		34,214		—		1,017,360		1,014,135		15,585		1,589		1,028,131
Collateralized mortgage obligations		1,067,314		10,630		2,928		1,075,016		1,120,363		2,244		12,676		1,109,931
	$	2,518,371	$	51,786	$	3,358	$	2,566,799	$	2,370,388	$	21,304	$	15,841	$	2,375,851

Amortized Cost and Fair Value of Debt Securities by Contractual Maturity

(in thousands)	Amortized		Fair
Debt Securities Available for Sale	Cost		Value
Due in one year or less	$	6,851	$	6,881
Due after one year through five years		78,862		79,865
Due after five years through ten years		366,738		377,314
Due after ten years		1,661,371		1,682,644
Total available for sale debt securities	$	2,113,822	$	2,146,704
	Amortized		Fair
Debt Securities Held to Maturity	Cost		Value
Due in one year or less	$	15,296	$	15,408
Due after one year through five years		415,949		417,841
Due after five years through ten years		356,084		358,834
Due after ten years		1,731,042		1,774,716
Total held to maturity securities	$	2,518,371	$	2,566,799

Available for Sale [Member]

Gain (Loss) on Investments [Line Items]

Securities with Unrealized Losses

Available for Sale
March 31, 2016	Losses < 12 months				Losses 12 months or >				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(in thousands)	Value		Losses		Value		Losses		Value		Losses
US Treasury and government agency securities	$	—		—	$	76	$	—	$	76	$	—
Municipal obligations		25,999		43		—		—		25,999		43
Mortgage-backed securities		160,058		170		69,703		554		229,761		724
Collateralized mortgage obligations		—		—		32,215		419		32,215		419
Equity securities		—		—		1,513		27		1,513		27
	$	186,057	$	213	$	103,507	$	1,000	$	289,564	$	1,213

Available for Sale
December 31, 2015	Losses < 12 months				Losses 12 months or >				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(in thousands)	Value		Losses		Value		Losses		Value		Losses
US Treasury and government agency securities	$	—	$	—	$	82	$	1	$	82	$	1
Municipal obligations		8,296		38		—		—		8,296		38
Mortgage-backed securities		831,156		8,257		116,126		2,925		947,282		11,182
Collateralized mortgage obligations		208,397		1,257		33,138		935		241,535		2,192
Equity securities		20		1		1,473		47		1,493		48
	$	1,047,869	$	9,553	$	150,819	$	3,908	$	1,198,688	$	13,461

Held to Maturity [Member]

Gain (Loss) on Investments [Line Items]

Securities with Unrealized Losses

Held to maturity
March 31, 2016	Losses < 12 months				Losses 12 months or >				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(in thousands)	Value		Losses		Value		Losses		Value		Losses
Municipal obligations	$	47,173	$	118	$	10,792	$	312	$	57,965	$	430
Collateralized mortgage obligations		8,871		15		314,160		2,913		323,031		2,928
	$	56,044	$	133	$	324,952	$	3,225	$	380,996	$	3,358

Held to maturity
December 31, 2015	Losses < 12 months				Losses 12 months or >				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	45,590	$	410	$	—	$	—	$	45,590	$	410
Municipal obligations		22,652		301		48,727		865		71,379		1,166
Mortgage-backed securities		349,635		1,589		—		—		349,635		1,589
Collateralized mortgage obligations		516,330		2,894		370,756		9,782		887,086		12,676
	$	934,207	$	5,194	$	419,483	$	10,647	$	1,353,690	$	15,841