Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010
Accounts receivable, allowance for doubtful accounts and billing adjustments	$ 4.9	$ 4.5
Property and equipment, accumulated depreciation and amortization	342.4	317.4
Computer software, accumulated amortization	535.2	497.6
Contract acquisition costs, accumulated amortization	280.5	260.7
Other intangible assets, accumulated amortization	$ 33.4	$ 26.9
Common stock, par value	$ 0.10	$ 0.10
Common stock, Authorized	600,000	600,000
Common stock, issued	201,602	201,326
Common stock, outstanding	192,908	194,528
Treasury stock, shares	8,694	6,798