Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Consolidated Balance Sheets
Accounts receivable, allowances for doubtful accounts and billing adjustments	$ 6.0
Other intangible assets, accumulated amortization	846.2	$ 802.0
Intangible assets - computer software, accumulated amortization	930.3	893.4
Property and equipment, accumulated depreciation and amortization	$ 523.0	$ 522.7
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, authorized (in shares)	600,000	600,000
Common stock, issued (in shares)	202,765	202,765
Common stock, outstanding (in shares)	176,943	180,586
Treasury stock (in shares)	25,822	22,179