Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Allowances for accounts receivable	$ 20.0	$ 47.0
Stockholders' equity:
Preferred stock, par value (USD per share)	$ 1.00	$ 1.00
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (USD per share)	$ 0.001	$ 0.001
Common stock, shares authorized	187,500,000	125,000,000
Common stock, shares, issued	71,565,394	67,667,468
Common stock, shares outstanding	69,372,412	65,474,486
Treasury stock, shares	2,192,982	2,192,982