Financial Instruments and Fair Value Measurements - Carrying Amounts and Estimated Fair Values (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Carrying amounts and estimated fair values of financial instruments
Carrying amount, liabilities	$ 3,538.9	$ 3,597.7
A/R Facility | Level 2
Carrying amounts and estimated fair values of financial instruments
Carrying amount, liabilities	99.0	73.0
Fair value, liabilities	99.0	73.0
Senior Credit Facility | Level 2
Carrying amounts and estimated fair values of financial instruments
Carrying amount, liabilities	643.5	1,268.1
Fair value, liabilities	645.5	1,256.5
7.25% Senior Notes | Level 1
Carrying amounts and estimated fair values of financial instruments
Carrying amount, liabilities	750.0	750.0
Fair value, liabilities	777.2	780.2
4.625% Senior Notes | Level 2
Carrying amounts and estimated fair values of financial instruments
Carrying amount, liabilities	556.7	0.0
Fair value, liabilities	541.9	0.0
Income tax receivable agreement | Level 3
Carrying amounts and estimated fair values of financial instruments
Carrying amount, liabilities	163.1	172.9
Fair value, liabilities	$ 130.0	$ 132.0