Investment Securities Available for Sale (Tables)

12 Months Ended

Dec. 31, 2015

Summary of Available-for-Sale Investment Securities

The amortized cost, gross unrealized gains and losses, and estimated fair values of investment securities available for sale at December 31, 2015 and 2014 are summarized below.



	December 31, 2015
(in thousands)	Amortized Cost		Gross Unrealized Gains	Gross Unrealized Losses		Fair Value
U.S. Treasury securities	$	43,125	232	—		43,357
U.S. Government agency securities	13,087		536	—		13,623
Securities issued by U.S. Government sponsored enterprises	126,520		389	—		126,909
Mortgage-backed securities issued by U.S. Government agencies	209,785		1,340	(1,121	)	210,004
Mortgage-backed securities issued by U.S. Government sponsored enterprises	2,645,107		7,874	(22,562	)	2,630,419
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	530,426		2,396	(3,225	)	529,597
State and municipal securities	4,343		92	(1	)	4,434
Equity securities	3,228		6,444	—		9,672
Other investments	20,177		—	(374	)	19,803
Total investment securities available for sale	$	3,595,798	19,303	(27,283	)	3,587,818

	December 31, 2014
(in thousands)	Amortized Cost ⁽¹⁾		Gross Unrealized Gains	Gross Unrealized Losses		Fair Value
U.S. Treasury securities	$	42,636	190	—		42,826
U.S. Government agency securities	26,426		898	—		27,324
Securities issued by U.S. Government sponsored enterprises	81,332		710	—		82,042
Mortgage-backed securities issued by U.S. Government agencies	177,678		2,578	(440	)	179,816
Mortgage-backed securities issued by U.S. Government sponsored enterprises	2,250,897		19,915	(9,131	)	2,261,681
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	414,562		4,856	(2,342	)	417,076
State and municipal securities	5,024		183	(1	)	5,206
Equity securities	3,228		3,520	—		6,748
Other investments	19,121		7	(441	)	18,687
Total investment securities available for sale	$	3,020,904	32,857	(12,355	)	3,041,406


⁽¹⁾	Amortized cost is adjusted for other-than-temporary impairment charges in 2014, which have been recognized in the consolidated statements of income, and were considered inconsequential.

Schedule of Unrealized Loss on Investments

Gross unrealized losses on investment securities and the fair value of the related securities, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at December 31, 2015 and December 31, 2014 are presented below.



	December 31, 2015
	Less than 12 Months			12 Months or Longer		Total
(in thousands)	Fair Value		Gross Unrealized Losses	Fair Value	Gross Unrealized Losses	Fair Value	Gross Unrealized Losses
Mortgage-backed securities issued by U.S. Government agencies	122,626		639	18,435	482	141,061	1,121
Mortgage-backed securities issued by U.S. Government sponsored enterprises	1,656,194		12,874	489,971	9,688	2,146,165	22,562
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	196,811		963	72,366	2,262	269,177	3,225
State and municipal securities	—		—	50	1	50	1
Other investments	14,985		15	4,818	359	19,803	374
Total	$	1,990,616	14,491	585,640	12,792	2,576,256	27,283

	December 31, 2014
	Less than 12 Months			12 Months or Longer		Total
(in thousands)	Fair Value		Gross Unrealized Losses	Fair Value	Gross Unrealized Losses	Fair Value	Gross Unrealized Losses
Mortgage-backed securities issued by U.S. Government agencies	—		—	21,488	440	21,488	440
Mortgage-backed securities issued by U.S. Government sponsored enterprises	251,134		763	798,282	8,368	1,049,416	9,131
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	20,338		61	119,172	2,281	139,510	2,342
State and municipal securities	—		—	45	1	45	1
Other investments	—		—	3,680	441	3,680	441
Total	$	271,472	824	942,667	11,531	1,214,139	12,355

Amortized Cost and Estimated Fair Value by Contractual Maturity of Investment Securities Available-for-Sale

For purposes of the maturity table, mortgage-backed securities and CMOs, which are not due at a single maturity date, have been classified based on the final contractual maturity date.



	Distribution of Maturities at December 31, 2015
(in thousands)	Within One Year		1 to 5 Years	5 to 10 Years	More Than 10 Years	No Stated Maturity	Total
Amortized Cost
U.S. Treasury securities	$	18,243	24,882	—	—	—	43,125
U.S. Government agency securities	—		6,676	6,411	—	—	13,087
Securities issued by U.S. Government sponsored enterprises	80,460		46,060	—	—	—	126,520
Mortgage-backed securities issued by U.S. Government agencies	—		—	18,745	191,040	—	209,785
Mortgage-backed securities issued by U.S. Government sponsored enterprises	—		725	1,648,680	995,702	—	2,645,107
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	—		—	—	530,426	—	530,426
State and municipal securities	1,067		699	—	2,577	—	4,343
Equity securities	—		—	—	—	3,228	3,228
Other investments	—		—	15,000	2,000	3,177	20,177
Total amortized cost	$	99,770	79,042	1,688,836	1,721,745	6,405	3,595,798
Fair Value
U.S. Treasury securities	$	18,243	25,114	—	—	—	43,357
U.S. Government agency securities	—		6,907	6,716	—	—	13,623
Securities issued by U.S. Government sponsored enterprises	80,634		46,275	—	—	—	126,909
Mortgage-backed securities issued by U.S. Government agencies	—		—	18,999	191,005	—	210,004
Mortgage-backed securities issued by U.S. Government sponsored enterprises	—		755	1,634,107	995,557	—	2,630,419
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	—		—	—	529,597	—	529,597
State and municipal securities	1,080		701	—	2,653	—	4,434
Equity securities	—		—	—	—	9,672	9,672
Other investments	—		—	14,985	1,745	3,073	19,803
Total fair value	$	99,957	79,752	1,674,807	1,720,557	12,745	3,587,818

Summary of Sales Transactions in the Investment Securities Available-for-Sale Portfolio

Other-than-temporary impairment charges of $88 thousand and $264 thousand respectively, are included in gross realized losses for the years ended December 31, 2014 and 2013. The specific identification method is used to reclassify gains and losses out of other comprehensive income at the time of sale.



(in thousands)	2015			2014			2013
Proceeds from sales of investment securities available for sale	$	347,954		20,815			407,718
Gross realized gains	$	4,356		$	1,419		$	3,822
Gross realized losses	(1,587		)	(88		)	(877		)
Investment securities gains, net	$	2,769		1,331			2,945