Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Accounts receivable, allowance for doubtful accounts and billing adjustments	$ 3.9	$ 4.1
Property and equipment, accumulated depreciation and amortization	359.1	357.1
Computer software, accumulated amortization	594.1	567.4
Contract acquisition costs, accumulated amortization	284.6	295.9
Other intangible assets, accumulated amortization	$ 46.8	$ 39.8
Common stock, par value	$ 0.10	$ 0.10
Common stock, Authorized	600,000	600,000
Common stock, issued	202,477	201,860
Common stock, outstanding	189,107	189,031
Treasury stock, shares	12,585	12,829