Stock-Based Compensation Narrative (Details) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2016 USD ($) shares	Sep. 30, 2015 shares		Sep. 30, 2016 USD ($) shares	Sep. 30, 2015 shares
Employee Stock Option [Member]
[Line Items]
Expected term (years)(1)		5 years 5 months 15 days	1 day	[1]	5 years 5 months 15 days	5 years 5 months 15 days
Award vesting rights					Options generally become exercisable in three equal annual installments beginning one year from the date of grant
Stock options expiration period (years)					10 years
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | $		$ 3.8			$ 3.8
Unrecognized compensation expense, Expected weighted average period for recognition (years)					2 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross			0		191,000	207,000
Long Term Performance Restricted Stock Award [Member]
[Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period			0
Performance Condition Vesting Range, Lower Range Limit					0.00%
Performance Condition Vesting Range, Upper Range Limit					160.00%
Market Condition Multiplier, Lower Range Limit					75.00%
Market Condition Multiplier, Upper Range Limit					125.00%
Possible Total Percentage of Shares Vested, Lower Range Limit					0.00%
Possible Total Percentage of Shares Vested, Upper Range Limit					200.00%
Restricted Stock Units (RSUs) [Member]
[Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	[2]				196,000	319,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | $		25.3			$ 25.3
Unrecognized compensation expense, Expected weighted average period for recognition (years)					2 years
Award vesting period					3 years
Phantom Share Units (PSUs) [Member]
[Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period					63,000
Deferred Compensation Share-based Arrangements, Liability, Current | $		0.7			$ 0.7
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | $		$ 2.8			$ 2.8
Unrecognized compensation expense, Expected weighted average period for recognition (years)					2 years 5 months
Employee Stock Purchase Plan [Member]
[Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		371,000			371,000
ESPP, maximum percentage of employee salary eligible for participation		10.00%			10.00%
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Purchase Date					5.00%
Long Term Performance Restricted Stock Award [Member] | Restricted Stock Units (RSUs) [Member]
[Line Items]
Expected term (years)(1)		2 years 3 months 15 days	1 day	[3]	1 year 10 months	2 years 1 month
Stock Incentive Plan [Member]
[Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized		7,473,956			7,473,956
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		2,111,769			2,111,769
Reduction in stock options available for issue		1			1
Authorized share reserve reduction in awards other than stock options or share appreciation rights available for issue, conversion ratio		1.7			1.7

[1] There were no employee stock options granted for the three months ended September 30, 2015.

[2] Restricted stock units granted in 2015 and 2016 do not include awards under the Performance Award Agreement for the respective years, as these awards are not granted until attainment of annual performance goals has been determined at the conclusion of the performance period, which had not occurred as of September 30, 2015 and 2016, respectively.

[3] There were no long-term performance restricted stock units granted for the three months ended September 30, 2015.