Share-Based Compensation, Other Equity Awards (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Equity Instruments Other than Options Activity [Roll Forward]
Balance at January 1 (in shares)	1,025
Granted (in shares)	522	496	588
Forfeited (in shares)	(80)
Vested (in shares)	(530)	(800)	(500)
Dividend equivalents (in shares)	47
Balance at December 31 (in shares)	984	1,025
Equity Instruments Other than Options, Weighted Average Grant Date Fair Value [Abstract]
Balance at January 1, weighted average grant date fair value (in dollars per share)	$ 32.81
Granted, weighted average grant date fair value (in dollars per share)	36.00	$ 36.09	$ 29.90
Forfeited, weighted average grant date fair value (in dollars per share)	33.48
Vested, weighted average grant date fair value (in dollars per share)	29.92
Dividend equivalents, weighted average grant date fair value (in dollars per share)	33.64
Balance at December 31, weighted average grant date fair value (in dollars per share)	$ 36.05	$ 32.81
Equity Instruments Other than Options, Additional Disclosures [Abstract]
Award Vesting Period (in years)	3 years
Total fair value of nonvested equity awards	$ 40.0
Weighted average remaining contractual life of nonvested equity awards (in years)	1 year 8 months
Total fair value of equity awards vested during the period	$ 21.6	$ 27.1	$ 19.6
Performance-based awards [Member]
Equity Instruments Other than Options, Additional Disclosures [Abstract]
Award Vesting Period (in years)	3 years
Service-based awards [Member]
Equity Instruments Other than Options Activity [Roll Forward]
Granted (in shares)	300	300	400
Equity Award Granted Between 2011 and 2013 | Performance-based awards [Member] | Minimum
Equity Instruments Other than Options, Additional Disclosures [Abstract]
Percentage payout for performance-based equity awards	0.00%
Equity Award Granted Between 2011 and 2013 | Performance-based awards [Member] | Maximum
Equity Instruments Other than Options, Additional Disclosures [Abstract]
Percentage payout for performance-based equity awards	150.00%
Equity Award Granted Between 2014 and 2016 | Performance-based awards [Member] | Minimum
Equity Instruments Other than Options, Additional Disclosures [Abstract]
Percentage payout for performance-based equity awards	0.00%
Equity Award Granted Between 2014 and 2016 | Performance-based awards [Member] | Maximum
Equity Instruments Other than Options, Additional Disclosures [Abstract]
Percentage payout for performance-based equity awards	200.00%