Consolidated Statements of Equity (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Dividends declared per share (in dollars per share)			$ 0.75
Stock-based compensation expense, discontinued operations			$ 6.0
Restricted stock and restricted stock unit vesting, related tax benefit	$ 0.6	$ 2.2	$ 0.7