Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Accounts receivable, allowance for doubtful accounts and billing adjustments	$ 3.7	$ 4.1
Property and equipment, accumulated depreciation and amortization	365.4	357.1
Computer software, accumulated amortization	584.2	567.4
Contract acquisition costs, accumulated amortization	279.5	295.9
Other intangible assets, accumulated amortization	$ 43.5	$ 39.8
Common stock, par value	$ 0.10	$ 0.10
Common stock, Authorized	600,000	600,000
Common stock, Issued	202,447	201,860
Common stock, Outstanding	189,773	189,031
Treasury stock, shares	12,674	12,829