Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2007	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
IPC | General Advisory And Management Services
Related Party Transaction
Specified amount of annual fees for ongoing advisory and management services	$ 0.5
Annual fee for ongoing advisory and management services as a percentage of adjusted EBITDA	0.75%
Amount incurred		0.3	0.2	0.6	0.5
Ryan | Operating Lease Services
Related Party Transaction
Number of members of the board of directors also serving as directors of a related party		1		1
Amount incurred		0.1	0.1	0.2	0.2
CT Partners | Executive Positions Search Services
Related Party Transaction
Number of members of the board of directors also serving as directors of a related party		1		1
Amount incurred		$ 0.1	$ 0	$ 0.2	$ 0.1