Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Accounts receivable allowances	$ 17.6	$ 47.0
Preferred stock, par value (usd per share)	$ 1.00	$ 1.00
Preferred stock, authorized (in shares)	5,000,000	5,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (usd per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	187,500,000	125,000,000
Common stock, issued (in shares)	71,767,371	67,667,468
Common stock, outstanding (in shares)	69,574,389	65,474,486
Treasury stock (in shares)	2,192,982	2,192,982