Investment Securities Investment Securities Unrealized losses and fair value of securities (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Sep. 30, 2014	Mar. 31, 2014
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	$ (7)	$ (2,437)
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	2,649	51,174
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	(3,069)	(2,335)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	80,396	38,238
Available-for-sale Securities, Gross Unrealized Loss	(3,076)	(4,772)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	83,045	89,412
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	0	(283)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0	4,796
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	(144)	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	4,887	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss	(144)	(283)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	4,887	4,796
Securities Continuous Loss Position Less than 12 months	(7)	(2,720)
Securities Continuous Unrealized Loss Position Less than 12 months Fair Value	2,649	55,970
Securities, Continuous Unrealized Loss Position ,12 months or Longer	(3,213)	(2,335)
Securities, Continuous Unrealized Loss Position, 12 months or Longer, Fair Value	85,283	38,238
Unrealized Loss on Securities	(3,220)	(5,055)
Securities, Continuous Unrealized Loss Position, fair value	87,932	94,208
Mortgage-backed securities
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	(4)	(322)
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	652	7,569
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	(788)	(1,015)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	24,940	20,123
Available-for-sale Securities, Gross Unrealized Loss	(792)	(1,337)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	25,592	27,692
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	0	(283)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0	4,796
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	(144)	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	4,887	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss	(144)	(283)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	4,887	4,796
US Government Agency Securities
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	(3)	(1,646)
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	1,997	34,074
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	(1,911)	(1,320)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	45,826	18,115
Available-for-sale Securities, Gross Unrealized Loss	(1,914)	(2,966)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	47,823	52,189
Other
Schedule of Investments [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	0	(469)
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0	9,531
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	(370)	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	9,630	0
Available-for-sale Securities, Gross Unrealized Loss	(370)	(469)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 9,630	$ 9,531