Condensed Consolidated Statement of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Other Capital	Treasury Stock	Accumulated Deficit	Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting guidance	$ 0.3		$ 0.3
Beginning balance (in shares) at Dec. 31, 2016		69.2
Beginning balance at Dec. 31, 2016	34.5	$ 6.9	456.9	$ (64.5)	$ (61.8)	$ (303.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	30.2				30.2
Amortization of actuarial losses and prior service credits, net of income taxes	19.1					19.1
Conversion of debt to common stock (in shares)		3.9
Conversion of debt to common stock	35.6	$ 0.4	35.2
Reclassification from redeemable common stock (in shares)		0.1
Reclassification from redeemable common stock	0.9		0.9
Repurchase of shares for withholding taxes and option costs under employee equity plans (in shares)		(0.4)
Repurchase of shares for withholding taxes and option costs under employee equity plans	(5.7)		(5.7)
Stock-based compensation and other, net (in shares)		0.5
Stock-based compensation and shares issued under equity plans	9.8		9.8
Ending balance (in shares) at Jun. 30, 2017		73.3
Ending balance at Jun. 30, 2017	$ 124.7	$ 7.3	$ 497.4	$ (64.5)	$ (31.6)	$ (283.9)