Debt (Details Textual) (USD $) In Millions, unless otherwise specified	9 Months Ended								0 Months Ended								0 Months Ended		12 Months Ended		0 Months Ended	1 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Sep. 30, 2013 Senior notes, due 2019	Jan. 23, 2013 Senior notes, due 2019	Dec. 31, 2012 Senior notes, due 2019	Sep. 30, 2013 Partnership notes, due 2020	Dec. 31, 2012 Partnership notes, due 2020	Jan. 24, 2013 Term loan	Sep. 30, 2013 Term loan		Jan. 23, 2013 Term loan	Dec. 31, 2012 Term loan		Sep. 30, 2013 Incremental credit facility	Sep. 30, 2013 Revolving credit facility	Aug. 28, 2013 IPO Partnership notes, due 2020	Jan. 24, 2013 IPO Partnership notes, due 2020	Dec. 31, 2012 IPO Partnership notes, due 2020	Jan. 23, 2013 IPO Partnership notes, due 2020	Jan. 24, 2013 IPO Term loan	Jan. 31, 2013 IPO Term loan	Jan. 23, 2013 IPO Term loan	Sep. 30, 2013 IPO Revolving credit facility	Aug. 28, 2013 IPO Revolving credit facility	Jan. 23, 2013 IPO Revolving credit facility	Aug. 28, 2013 IPO Uncommitted incremental revolving credit facility
Line of Credit Facility [Line Items]
Long-term debt term (in years)									7 years
Long-term debt	$ 649.1		$ 723.4	$ 400.0	$ 400.0	$ 400.0	$ 150.0	$ 0		$ 99.1	[1]	$ 300.0	$ 323.4	[1]
Maximum borrowing capacity												75.0				150.0									150.0	100.0	100.0
Interest rate on senior notes (as a percent)				7.625%	7.625%	7.625%	7.375%	7.375%												7.375%
Letters of credit outstanding under revolving facility																2.1
Remaining letters of credit agreement amount															45.0	147.9								149.3
Repayment of long-term debt	225.0	2.5																			225.0
Write-off of unamortized debt issuance costs and original issue discount																							2.9
Debt issuance costs																	0.9	5.9	0.6			0.7
Senior notes																				150.0
Redeem partnership note percentage (as a percent)																		35.00%
Debt issuance costs expensed																		0.8
Amount of letters of credit outstanding																								$ 0.7

[1] Borrowed under the Company's Credit Agreement on July 26, 2011, as amended ("Credit Agreement").