Deferred Compensation Plan (Details) (USD $)	3 Months Ended			12 Months Ended
	Mar. 31, 2016	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Aug. 01, 2013	May 09, 2014 Subordinated Debt [Member]	Mar. 31, 2014 Subordinated Debt [Member]	Feb. 21, 2014 Subordinated Debt [Member]	Jan. 22, 2014 Subordinated Debt [Member]	Oct. 18, 2013 Subordinated Debt [Member]	Aug. 01, 2013 Subordinated Debt [Member]	Mar. 08, 2013 Subordinated Debt [Member]	Mar. 10, 2010 Subordinated Debt [Member]	Mar. 31, 2014 2014 [Member]	Mar. 31, 2014 2015 through 2017 [Member]
Debt Instrument, Repurchased Face Amount						$ 42,500,000	$ 50,000,000	$ 20,000,000	$ 30,000,000	$ 155,000,000	$ 324,000,000	$ 50,000,000	$ 28,500,000
RDU Plan, units authorized for issuance		28,500
RDU Plan, units outstanding		28,500
Deferred Compensation Arrangement with Individual, Requisite Service Period		P3Y0M0D
Redemption premium added to debt face amount, RDU plan				1,400,000
RDU plan cash retention pool					15,000,000
Charge for payment of RDU Plan cash retention pool				7,500,000
Second RDU Cash Retention Payment	7,500,000
RDU Plan, unrecognized compensation expense														7,000,000	7,000,000
RDU Plan, compensation expense		2,200,000	2,100,000
RDU Plan, liability		$ 24,100,000	$ 21,800,000