Securities (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Securities
Available-for-sale, Less Than Twelve Months, Estimated Fair Value	$ 334,474	$ 92,893
Available-for-sale, Less Than Twelve Months, Gross Unrealized Losses	(14,657)	(589)
Available-for-sale, Twelve Months or Longer, Estimated Fair Value	205	10,756
Available-for-sale, Twelve Months or Longer, Gross Unrealized Losses	(14)	(102)
Available-for-sale, Total, Estimated Fair Value	334,679	103,649
Available-for-sale, Total, Gross Unrealized Losses	(14,671)	(691)
Held-to-maturity, Less Than Twelve Months, Estimated Fair Value	1,031,627	413,699
Held-to-maturity, Less Than Twelve Months, Gross Unrealized Losses	(43,112)	(2,760)
Held-to-maturity, Twelve Months or Longer, Estimated Fair Value	151,609	12,259
Held-to-maturity, Twelve Months or Longer, Gross Unrealized Losses	(8,315)	(196)
Held-to-maturity, Total, Estimated Fair Value	1,183,236	425,958
Held-to-maturity, Total, Gross Unrealized Losses	(51,427)	(2,956)
GSE issuance REMICs and CMOs
Securities
Available-for-sale, Less Than Twelve Months, Estimated Fair Value	243,149	67,841
Available-for-sale, Less Than Twelve Months, Gross Unrealized Losses	(7,134)	(583)
Available-for-sale, Total, Estimated Fair Value	243,149	67,841
Available-for-sale, Total, Gross Unrealized Losses	(7,134)	(583)
Held-to-maturity, Less Than Twelve Months, Estimated Fair Value	719,715	413,651
Held-to-maturity, Less Than Twelve Months, Gross Unrealized Losses	(25,611)	(2,759)
Held-to-maturity, Twelve Months or Longer, Estimated Fair Value	151,581	12,259
Held-to-maturity, Twelve Months or Longer, Gross Unrealized Losses	(8,314)	(196)
Held-to-maturity, Total, Estimated Fair Value	871,296	425,910
Held-to-maturity, Total, Gross Unrealized Losses	(33,925)	(2,955)
Non-GSE issuance REMICs and CMOs
Securities
Available-for-sale, Twelve Months or Longer, Estimated Fair Value	132	10,709
Available-for-sale, Twelve Months or Longer, Gross Unrealized Losses	(1)	(86)
Available-for-sale, Total, Estimated Fair Value	132	10,709
Available-for-sale, Total, Gross Unrealized Losses	(1)	(86)
Held-to-maturity, Less Than Twelve Months, Estimated Fair Value	392
Held-to-maturity, Less Than Twelve Months, Gross Unrealized Losses	(10)
Held-to-maturity, Total, Estimated Fair Value	392
Held-to-maturity, Total, Gross Unrealized Losses	(10)
GSE pass-through certificates
Securities
Available-for-sale, Less Than Twelve Months, Estimated Fair Value	172	57
Available-for-sale, Less Than Twelve Months, Gross Unrealized Losses	(1)	(1)
Available-for-sale, Twelve Months or Longer, Estimated Fair Value	70	47
Available-for-sale, Twelve Months or Longer, Gross Unrealized Losses	(1)	(1)
Available-for-sale, Total, Estimated Fair Value	242	104
Available-for-sale, Total, Gross Unrealized Losses	(2)	(2)
Held-to-maturity, Less Than Twelve Months, Estimated Fair Value	230,795	48
Held-to-maturity, Less Than Twelve Months, Gross Unrealized Losses	(10,088)	(1)
Held-to-maturity, Twelve Months or Longer, Estimated Fair Value	28
Held-to-maturity, Twelve Months or Longer, Gross Unrealized Losses	(1)
Held-to-maturity, Total, Estimated Fair Value	230,823	48
Held-to-maturity, Total, Gross Unrealized Losses	(10,089)	(1)
Obligations of GSEs
Securities
Available-for-sale, Less Than Twelve Months, Estimated Fair Value	91,153	24,995
Available-for-sale, Less Than Twelve Months, Gross Unrealized Losses	(7,522)	(5)
Available-for-sale, Total, Estimated Fair Value	91,153	24,995
Available-for-sale, Total, Gross Unrealized Losses	(7,522)	(5)
Held-to-maturity, Less Than Twelve Months, Estimated Fair Value	80,725
Held-to-maturity, Less Than Twelve Months, Gross Unrealized Losses	(7,403)
Held-to-maturity, Total, Estimated Fair Value	80,725
Held-to-maturity, Total, Gross Unrealized Losses	(7,403)
Fannie Mae stock
Securities
Available-for-sale, Twelve Months or Longer, Estimated Fair Value	3
Available-for-sale, Twelve Months or Longer, Gross Unrealized Losses	(12)	(15)
Available-for-sale, Total, Estimated Fair Value	3
Available-for-sale, Total, Gross Unrealized Losses	$ (12)	$ (15)