CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Property and equipment, Accumulated depreciation	$ 37.6	$ 37.6
Common stock, par value
Common stock, shares authorized	180,000,000	180,000,000
Common stock, issued	92,302,299	92,302,299
Common stock, outstanding	92,282,030	92,285,408
Treasury stock, shares	20,269	16,891