Deferred Compensation Plan (Details) (USD $)	3 Months Ended			6 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Apr. 30, 2013	Dec. 31, 2012	Aug. 01, 2013 Senior Subordinated Notes [Member]	Mar. 10, 2010 Senior Subordinated Notes [Member]	Jun. 30, 2013 2013 through 2014 [Member]	Jun. 30, 2013 2015 through 2017 [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Debt Instrument, Repurchased Face Amount								$ 324,000,000	$ 28,500,000
RDU Plan, units authorized for issuance		28,500		28,500
RDU Plan, units outstanding		26,549		26,549
Deferred Compensation Arrangement with Individual, Requisite Service Period				P3Y0M0D
Deferred Compensation Arrangement with Individual, Distributions Paid						1,700,000
Charge for payment of RDU Plan cash retention pool	7,500,000
RDU Plan, unrecognized compensation expense										21,000,000	7,000,000
RDU Plan, compensation expense		2,200,000	2,100,000	4,300,000	4,200,000
RDU Plan, liability		$ 18,100,000		$ 18,100,000			$ 15,500,000