Other Non-Operating Expense (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Feb. 28, 2011	Dec. 31, 2011
Other Non-Operating Expense
Interest rate (as a percent)	6.75%	6.75%
6.75% senior subordinated notes due 2015
Other Non-Operating Expense
Senior subordinated notes redeemed	$ 73.5		$ 150.0
Face value			225
Interest rate (as a percent)	6.75%	6.75%	6.75%	6.75%
Call premium (as a percent)	1.125%		2.25%
Pre-tax charge incurred on call premium		$ 1.1	$ 4.9