Investment Securities (Tables)

3 Months Ended

Mar. 31, 2016

Investments [Abstract]

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 March 31, 2016 and December 31, 2015 are summarized below.

	March 31, 2016
(in thousands)	Amortized Cost		Gross Unrealized Gains	Gross Unrealized Losses		Fair Value
U.S. Treasury securities	$	43,147	559	—		43,706
U.S. Government agency securities	13,016		534	—		13,550
Securities issued by U.S. Government sponsored enterprises	126,305		297	—		126,602
Mortgage-backed securities issued by U.S. Government agencies	191,386		2,653	(143	)	193,896
Mortgage-backed securities issued by U.S. Government sponsored enterprises	2,599,118		24,787	(1,771	)	2,622,134
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	542,761		7,687	(393	)	550,055
State and municipal securities	3,964		76	(1	)	4,039
Equity securities	3,228		4,976	—		8,204
Other investments	20,194		286	(422	)	20,058
Total investment securities available for sale	$	3,543,119	41,855	(2,730	)	3,582,244
	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

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 March 31, 2016 and December 31, 2015, are presented below.

	March 31, 2016
	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	—		—	11,938	143	11,938	143
Mortgage-backed securities issued by U.S. Government sponsored enterprises	559,661		1,602	29,281	169	588,942	1,771
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	—		—	71,875	393	71,875	393
State and municipal securities	—		—	51	1	51	1
Other investments	—		—	4,771	422	4,771	422
Total	$	559,661	1,602	117,916	1,128	677,577	2,730
	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

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 March 31, 2016
(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	$	18,256	24,891	—	—	—	43,147
U.S. Government agency securities	—		6,614	6,402	—	—	13,016
Securities issued by U.S. Government sponsored enterprises	80,240		46,065	—	—	—	126,305
Mortgage-backed securities issued by U.S. Government agencies	—		—	17,447	173,939	—	191,386
Mortgage-backed securities issued by U.S. Government sponsored enterprises	—		566	1,333,864	1,264,688	—	2,599,118
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	—		—	—	542,761	—	542,761
State and municipal securities	1,037		350	—	2,577	—	3,964
Equity securities	—		—	—	—	3,228	3,228
Other investments	—		—	15,000	2,000	3,194	20,194
Total amortized cost	$	99,533	78,486	1,372,713	1,985,965	6,422	3,543,119
Fair Value
U.S. Treasury securities	$	18,256	25,450	—	—	—	43,706
U.S. Government agency securities	—		6,849	6,701	—	—	13,550
Securities issued by U.S. Government sponsored enterprises	80,398		46,204	—	—	—	126,602
Mortgage-backed securities issued by U.S. Government agencies	—		—	17,810	176,086	—	193,896
Mortgage-backed securities issued by U.S. Government sponsored enterprises	—		588	1,341,168	1,280,378	—	2,622,134
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	—		—	—	550,055	—	550,055
State and municipal securities	1,049		352	—	2,638	—	4,039
Equity securities	—		—	—	—	8,204	8,204
Other investments	—		—	15,287	1,638	3,133	20,058
Total fair value	$	99,703	79,443	1,380,966	2,010,795	11,337	3,582,244

Schedule of Activity for Available-for-Sale Securities

Proceeds from sales, gross gains, and gross losses on sales of securities available for sale for the three months ended March 31, 2016 and 2015 are presented below. The specific identification method is used to reclassify gains and losses out of other comprehensive income at the time of sale.

	Three Months Ended March 31,
(in thousands)	2016			2015
Proceeds from sales of investment securities available for sale	$	243,609		32,419
Gross realized gains	954			725
Gross realized losses	(887		)	—
Investment securities gains, net	$	67		725