Stock-Based Compensation Stock-Based Compensation Narrative (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Employee Stock Option [Member]
[Line Items]
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
Unrecognized compensation expense	$ 4.6
Unrecognized compensation expense, Expected weighted average period for recognition (years)	2 years 2 months 15 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	204,000	147,000
Long Term Performance Restricted Stock Award [Member]
[Line Items]
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]
Unrecognized compensation expense	$ 30.6
Unrecognized compensation expense, Expected weighted average period for recognition (years)	2 years 2 months 0 days
Award vesting period	3 years
Employee Stock Purchase Plan [Member]
[Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	435,000
ESPP, maximum percentage of employee salary eligible for participation	10.00%
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Purchase Date	5.00%
Stock Incentive Plan [Member]
[Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	7,473,956
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	2,752,503
Reduction in stock options available for issue	1
Authorized share reserve reduction in awards other than stock options or share appreciation rights available for issue, conversion ratio	1.7