Investment Securities (Tables)

6 Months Ended

Jun. 30, 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 June 30, 2016 and December 31, 2015 are summarized below.

	June 30, 2016
(in thousands)	Amortized Cost		Gross Unrealized Gains	Gross Unrealized Losses		Fair Value
U.S. Treasury securities	$	73,741	1,082	—		74,823
U.S. Government agency securities	13,006		443	—		13,449
Securities issued by U.S. Government sponsored enterprises	50,063		54	—		50,117
Mortgage-backed securities issued by U.S. Government agencies	189,281		3,583	(81	)	192,783
Mortgage-backed securities issued by U.S. Government sponsored enterprises	2,544,204		37,817	(352	)	2,581,669
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	625,458		10,298	(142	)	635,614
State and municipal securities	3,000		47	(1	)	3,046
Equity securities	3,228		5,503	—		8,731
Other investments	20,210		333	(416	)	20,127
Total investment securities available for sale	$	3,522,191	59,160	(992	)	3,580,359
	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 June 30, 2016 and December 31, 2015, are presented below.

	June 30, 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	—		—	9,785	81	9,785	81
Mortgage-backed securities issued by U.S. Government sponsored enterprises	170,365		352	—	—	170,365	352
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	—		—	27,827	142	27,827	142
State and municipal securities	—		—	53	1	53	1
Other investments	—		—	4,794	416	4,794	416
Total	$	170,365	352	42,459	640	212,824	992
	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 June 30, 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	$	18,758	54,983	—	—	—	73,741
U.S. Government agency securities	—		6,613	6,393	—	—	13,006
Securities issued by U.S. Government sponsored enterprises	50,063		—	—	—	—	50,063
Mortgage-backed securities issued by U.S. Government agencies	—		—	16,261	173,020	—	189,281
Mortgage-backed securities issued by U.S. Government sponsored enterprises	—		454	1,254,247	1,289,503	—	2,544,204
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	—		—	—	625,458	—	625,458
State and municipal securities	184		350	—	2,466	—	3,000
Equity securities	—		—	—	—	3,228	3,228
Other investments	—		—	15,000	2,000	3,210	20,210
Total amortized cost	$	69,005	62,400	1,291,901	2,092,447	6,438	3,522,191
Fair Value
U.S. Treasury securities	$	18,758	56,065	—	—	—	74,823
U.S. Government agency securities	—		6,800	6,649	—	—	13,449
Securities issued by U.S. Government sponsored enterprises	50,117		—	—	—	—	50,117
Mortgage-backed securities issued by U.S. Government agencies	—		—	16,653	176,130	—	192,783
Mortgage-backed securities issued by U.S. Government sponsored enterprises	—		469	1,269,397	1,311,803	—	2,581,669
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	—		—	—	635,614	—	635,614
State and municipal securities	184		350	—	2,512	—	3,046
Equity securities	—		—	—	—	8,731	8,731
Other investments	—		—	15,333	1,625	3,169	20,127
Total fair value	$	69,059	63,684	1,308,032	2,127,684	11,900	3,580,359

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 six and three months ended June 30, 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.

	Six Months Ended June 30,				Three Months Ended June 30,
(in thousands)	2016			2015	2016		2015
Proceeds from sales of investment securities available for sale	$	243,609		82,156	$	—	49,737
Gross realized gains	954			2,710	—		1,985
Gross realized losses	(887		)	—	—		—
Investment securities gains, net	$	67		2,710	$	—	1,985