Shareholders' Equity IPO- and secondary-offering related expenses (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
IPO- and secondary-offering related expenses [Abstract]
Accelerated share based compensation expense and related employer payroll taxes	$ 40.7	[1]
Charge for payment of RDU Plan cash retention pool	7.5	[2]
Net proceeds used for termination of Management Services Agreement	24.4	[3]
Other IPO- and secondary-offering related expenses	2.4
IPO- and secondary-offering related expenses	$ 75.0		$ 0	$ 0

[1] See Note 10 for additional discussion of the impact of the IPO on the Company's equity awards.

[2] See Note 12 for additional discussion of this transaction

[3] Represents the payment of a termination fee to affiliates of the Sponsors in connection with the termination of the management services agreement with such entities.