Securities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Securities
Available-for-sale, amortized cost	$ 414,457	$ 330,481
Available-for-sale, Gross Unrealized Gains	1,904	6,510
Available-for-sale, Gross Unrealized Losses	(14,671)	(691)
Total available-for-sale securities	401,690	336,300
Held-to-maturity, amortized cost	1,849,526	1,700,141
Held-to-maturity, Gross Unrealized Gains	13,023	27,905
Held-to-maturity, Gross Unrealized Losses	(51,427)	(2,956)
Held-to-maturity, estimated fair value	1,811,122	1,725,090
Residential mortgage-backed securities
Securities
Available-for-sale, amortized cost	315,767	231,796
Available-for-sale, Gross Unrealized Gains	1,904	6,296
Available-for-sale, Gross Unrealized Losses	(7,137)	(671)
Total available-for-sale securities	310,534	237,421
Held-to-maturity, amortized cost	1,760,812	1,699,485
Held-to-maturity, Gross Unrealized Gains	13,023	27,905
Held-to-maturity, Gross Unrealized Losses	(44,024)	(2,956)
Held-to-maturity, estimated fair value	1,729,811	1,724,434
GSE issuance REMICs and CMOs
Securities
Available-for-sale, amortized cost	292,131	200,152
Available-for-sale, Gross Unrealized Gains	1,077	5,258
Available-for-sale, Gross Unrealized Losses	(7,134)	(583)
Total available-for-sale securities	286,074	204,827
Held-to-maturity, amortized cost	1,474,506	1,693,437
Held-to-maturity, Gross Unrealized Gains	12,877	27,787
Held-to-maturity, Gross Unrealized Losses	(33,925)	(2,955)
Held-to-maturity, estimated fair value	1,453,458	1,718,269
Non-GSE issuance REMICs and CMOs
Securities
Available-for-sale, amortized cost	7,516	11,296
Available-for-sale, Gross Unrealized Gains	57	9
Available-for-sale, Gross Unrealized Losses	(1)	(86)
Total available-for-sale securities	7,572	11,219
Held-to-maturity, amortized cost	3,833	5,791
Held-to-maturity, Gross Unrealized Gains	61	112
Held-to-maturity, Gross Unrealized Losses	(10)
Held-to-maturity, estimated fair value	3,884	5,903
GSE pass-through certificates
Securities
Available-for-sale, amortized cost	16,120	20,348
Available-for-sale, Gross Unrealized Gains	770	1,029
Available-for-sale, Gross Unrealized Losses	(2)	(2)
Total available-for-sale securities	16,888	21,375
Held-to-maturity, amortized cost	282,473	257
Held-to-maturity, Gross Unrealized Gains	85	6
Held-to-maturity, Gross Unrealized Losses	(10,089)	(1)
Held-to-maturity, estimated fair value	272,469	262
Obligations of GSEs
Securities
Available-for-sale, amortized cost	98,675	98,670
Available-for-sale, Gross Unrealized Gains		214
Available-for-sale, Gross Unrealized Losses	(7,522)	(5)
Total available-for-sale securities	91,153	98,879
Held-to-maturity, amortized cost	88,128
Held-to-maturity, Gross Unrealized Losses	(7,403)
Held-to-maturity, estimated fair value	80,725
Fannie Mae stock
Securities
Available-for-sale, amortized cost	15	15
Available-for-sale, Gross Unrealized Losses	(12)	(15)
Total available-for-sale securities	3
Other
Securities
Held-to-maturity, amortized cost	586	656
Held-to-maturity, estimated fair value	$ 586	$ 656