Stock-Based Compensation Performance Share Units Activity (Details)	9 Months Ended
	Sep. 30, 2017 $ / shares shares
PSU
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding, shares, beginning of period (shares)	347,000
Granted (shares)	117,777	[1]
Vested (shares)	(165,113)
Forfeited (shares)	(46,836)
Adjustment due to the 2017 Special Cash Dividend	24,244	[1],[2]
Outstanding and nonvested, shares, end of period (shares)	271,248
Outstanding, shares, beginning of period (shares), not yet granted	19,725
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Outstanding, weighted average fair value, beginning of period (usd per share) | $ / shares	$ 27.23
Granted, weighted average fair value (usd per share) | $ / shares	31.45	[1]
Vested, weighted average fair value (usd per share) | $ / shares	32.67
Forfeited, weighted average fair value (usd per share) | $ / shares	33.73
Outstanding and nonvested, weighted average fair value, end of period (usd per share) | $ / shares	$ 22.20
PSU Dividend Equivalent Unit (DEU)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Granted (shares)	3,503
Dividend equivalent units vested (shares)	(3,726)
Dividend equivalent units forfeited (shares)	(5,601)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Granted, weighted average fair value (usd per share) | $ / shares	$ 38.68
Dividend equivalent units vested, weighted average fair value (usd per share) | $ / shares	32.50
Dividend equivalent units forfeited, weighted average fair value (usd per share) | $ / shares	$ 40.72

[1] Represents shares of PSUs for which performance targets have been established and which are deemed granted under U.S. GAAP.

[2] Excludes 19,725 PSUs which have not yet been deemed granted under U.S. GAAP.