Non-operating Expense (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				1 Months Ended			1 Months Ended		12 Months Ended
	Jun. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jun. 30, 2013 Senior secured credit facility - revolving loan due 2018	Jun. 30, 2013 Previous term Loan	Jun. 30, 2013 Previous revolving credit line	Jun. 30, 2012 6.75% senior subordinated notes due 2015	Feb. 28, 2011 6.75% senior subordinated notes due 2015	Dec. 31, 2012 6.75% senior subordinated notes due 2015	Dec. 31, 2011 6.75% senior subordinated notes due 2015
Other non-operating expense
Pre-tax charge incurred on call premium	$ 1.0									$ 1.1	$ 4.9
Maximum borrowing capacity					600.0	82.5	360.0
Debt maturity period					5 years
Senior subordinated notes redeemed								$ 73.5	$ 150.0
Interest rate (as a percent)		6.75%	6.75%	6.75%				6.75%	6.75%
Call premium (as a percent)								1.125%	2.25%