Stock-Based Compensation Stock-Based Compensation Narrative (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended							0 Months Ended
	Sep. 30, 2013 Employee Stock Option [Member]	Sep. 30, 2012 Employee Stock Option [Member]	Sep. 30, 2013 Employee Stock Option [Member]	Sep. 30, 2012 Employee Stock Option [Member]	Sep. 30, 2013 Long Term Performance Restricted Stock Award [Member]	Sep. 30, 2013 Long Term Performance Restricted Stock Award [Member]	Sep. 30, 2013 Restricted Stock Units (RSUs) [Member]		Sep. 30, 2012 Restricted Stock Units (RSUs) [Member]		Sep. 30, 2013 Employee Stock Purchase Plan [Member]	Sep. 30, 2013 Stock Incentive Plan [Member]	Oct. 01, 2013 Subsequent Event [Member] Employee Stock Purchase Plan [Member]
[Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period					0		255,000	[1]	452,000	[1]
Number of shares authorized for issuance under the share based compensation plan												3,500,000
Number of shares available for future grant under the Stock Incentive Plan											530,000	453,869
Share-based Compensation Arrangement by Share-based Payment Award, Description												The Stock Incentive Plan shares are subject to a fungible share provision such that, with respect to grants made after December 31, 2009, the authorized share reserve is reduced by (i) one share for every one share subject to a stock option or share appreciation right granted under the Plan and (ii) 1.7 shares for every one share of common stock that was subject to an award other than an option or stock appreciation right.
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
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	0	0	128,000	54,000
Unrecognized compensation expense	$ 3.6		$ 3.6				$ 19.7
Unrecognized compensation expense, Expected weighted average period for recognition (years)			2 years 1 month 10 days				1 year 8 months 26 days
Award vesting period							3 years
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%
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											15.00%		5.00%
Number of shares available for future grant under the Employee Stock Purchase Plan											530,000	453,869

[1] Restricted stock units granted in 2012 and 2013 do not include awards under the Performance Award Agreement for the respective years, as these awards are not granted until final attainment of performance goals has been determined at the conclusion of the performance period, which had not occurred as of September 30, 2012 and 2013, respectively.