Securities (Tables)

6 Months Ended

Jun. 30, 2016

Gain (Loss) on Investments [Line Items]

Amortized Cost and Fair Value of Securities Available for Sale

Securities Available for Sale
(in thousands)	June 30, 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	$	116	$	—	$	—	$	116	$	135	$	—	$	1	$	134
Municipal obligations		151,557		4,735		—		156,292		39,410		235		38		39,607
Mortgage-backed securities		1,867,063		39,413		130		1,906,346		1,750,168		19,387		11,182		1,758,373
Collateralized mortgage obligations		238,165		3,181		—		241,346		291,085		140		2,192		289,033
Corporate debt securities		3,500		—		—		3,500		3,500		—		—		3,500
Equity securities		877		335		—		1,212		2,447		358		48		2,757
	$	2,261,278	$	47,664	$	130	$	2,308,812	$	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)	June 30, 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	$	1,047	$	—	$	51,047	$	50,000	$	—	$	410	$	49,590
Municipal obligations		496,999		18,158		372		514,785		185,890		3,475		1,166		188,199
Mortgage-backed securities		946,722		40,068		—		986,790		1,014,135		15,585		1,589		1,028,131
Collateralized mortgage obligations		1,003,837		13,543		918		1,016,462		1,120,363		2,244		12,676		1,109,931
	$	2,497,558	$	72,816	$	1,290	$	2,569,084	$	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	$	6,825	$	6,839
Due after one year through five years		53,816		54,914
Due after five years through ten years		391,388		405,008
Due after ten years		1,808,372		1,840,839
Total available for sale debt securities	$	2,260,401	$	2,307,600
	Amortized		Fair
Debt Securities Held to Maturity	Cost		Value
Due in one year or less	$	15,700	$	15,779
Due after one year through five years		136,327		140,424
Due after five years through ten years		403,112		416,795
Due after ten years		1,942,419		1,996,086
Total held to maturity securities	$	2,497,558	$	2,569,084

Available for Sale [Member]

Gain (Loss) on Investments [Line Items]

Securities with Unrealized Losses

Available for Sale
June 30, 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	$	—		—	$	70	$	—	$	70	$	—
Mortgage-backed securities		13,310		90		7,929		40		21,239		130
	$	13,310	$	90	$	7,999	$	40	$	21,309	$	130

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
June 30, 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	$	—	$	—	$	12,476	$	372	$	12,476	$	372
Collateralized mortgage obligations		1,392		2		149,600		916		150,992		918
	$	1,392	$	2	$	162,076	$	1,288	$	163,468	$	1,290

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