Securities (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Securities
Available-for-sale, amortized cost	$ 409,480	$ 383,631
Available-for-sale, gross unrealized gains	5,860	4,282
Available-for-sale, gross unrealized losses	(1,937)	(3,554)
Total available-for-sale securities	413,403us-gaap_AvailableForSaleSecurities	384,359us-gaap_AvailableForSaleSecurities
Total held-to-maturity securities	2,119,542us-gaap_HeldToMaturitySecurities	2,133,804us-gaap_HeldToMaturitySecurities
Held-to-maturity, gross unrealized gains	27,724	17,605
Held-to-maturity, gross unrealized losses	(9,359)	(20,038)
Held-to-maturity securities, fair value	2,137,907	2,131,371
GSE issuance REMICs and CMOs
Securities
Available-for-sale, amortized cost	294,026	266,946
Available-for-sale, gross unrealized gains	5,238	3,608
Available-for-sale, gross unrealized losses	(829)	(1,556)
Total available-for-sale securities	298,435	268,998
Total held-to-maturity securities	1,490,860	1,575,402
Held-to-maturity, gross unrealized gains	20,981	14,536
Held-to-maturity, gross unrealized losses	(7,138)	(14,041)
Held-to-maturity securities, fair value	1,504,703	1,575,897
Non-GSE issuance REMICs and CMOs
Securities
Available-for-sale, amortized cost	4,524	5,071
Available-for-sale, gross unrealized gains	28	34
Available-for-sale, gross unrealized losses	(1)	(1)
Total available-for-sale securities	4,551	5,104
Total held-to-maturity securities	2,299	2,482
Held-to-maturity, gross unrealized gains	27	31
Held-to-maturity, gross unrealized losses	(7)	(7)
Held-to-maturity securities, fair value	2,319	2,506
GSE pass-through certificates
Securities
Available-for-sale, amortized cost	12,234	12,919
Available-for-sale, gross unrealized gains	594	640
Available-for-sale, gross unrealized losses	(2)	(2)
Total available-for-sale securities	12,826	13,557
Total held-to-maturity securities	271,379	281,685
Held-to-maturity, gross unrealized gains	3,431	2,442
Held-to-maturity, gross unrealized losses	(1,665)	(3,877)
Held-to-maturity securities, fair value	273,145	280,250
Total residential mortgage-backed securities
Securities
Available-for-sale, amortized cost	310,784	284,936
Available-for-sale, gross unrealized gains	5,860	4,282
Available-for-sale, gross unrealized losses	(832)	(1,559)
Total available-for-sale securities	315,812	287,659
Total held-to-maturity securities	1,764,538	1,859,569
Held-to-maturity, gross unrealized gains	24,439	17,009
Held-to-maturity, gross unrealized losses	(8,810)	(17,925)
Held-to-maturity securities, fair value	1,780,167	1,858,653
Obligations of GSEs
Securities
Available-for-sale, amortized cost	98,681	98,680
Available-for-sale, gross unrealized losses	(1,092)	(1,982)
Total available-for-sale securities	97,589	96,698
Total held-to-maturity securities	128,769	119,336
Held-to-maturity, gross unrealized gains	536	42
Held-to-maturity, gross unrealized losses	(476)	(1,523)
Held-to-maturity securities, fair value	128,829	117,855
Fannie Mae stock
Securities
Available-for-sale, amortized cost	15	15
Available-for-sale, gross unrealized losses	(13)	(13)
Total available-for-sale securities	2	2
Multi-family mortgage-backed securities:
Securities
Total held-to-maturity securities	225,738	154,381
Held-to-maturity, gross unrealized gains	2,748	554
Held-to-maturity, gross unrealized losses	(73)	(590)
Held-to-maturity securities, fair value	228,413	154,345
Equity Securities Other and Other Debt Securities [Member]
Securities
Total held-to-maturity securities	497	518
Held-to-maturity, gross unrealized gains	1
Held-to-maturity securities, fair value	$ 498	$ 518

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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