Stockholders' Equity (Details) (USD $) | 0 Months Ended | 3 Months Ended | 9 Months Ended |
Share data in Thousands, except Per Share data, unless otherwise specified | Feb. 01, 2012 | Sep. 30, 2013 | Sep. 30, 2012 | Sep. 30, 2013 | Sep. 30, 2012 |
Number of Awards | ' | ' | ' | ' | ' |
Cash received under program | ' | ' | ' | $1,474,000 | $612,000 |
Employee Stock Purchase Plan | ' | ' | ' | ' | ' |
Weighted-average assumptions used in the Black-Scholes option pricing model | ' | ' | ' | ' | ' |
Expected stock price volatility (as a percent) | ' | 65.00% | 68.00% | 67.00% | 68.00% |
Risk-free interest rate (as a percent) | ' | 0.10% | 0.92% | 0.12% | 0.92% |
Expected life | ' | '6 months | '6 months | '6 months | '6 months |
Expected dividend yield (as a percent) | ' | 0.00% | 0.00% | 0.00% | 0.00% |
Share-based compensation expense additional disclosures | ' | ' | ' | ' | ' |
After tax stock-based compensation expense | ' | 164,000 | 113,000 | 493,000 | 321,000 |
Stock-based compensation cost related to non-vested equity awards not yet recognized as an expense | ' | 144,000 | ' | 144,000 | ' |
Number of Awards | ' | ' | ' | ' | ' |
Term of Employee Stock Purchase Plan | '10 years | ' | ' | ' | ' |
Employee Stock Purchase Plan Payroll Withholding Period | ' | ' | ' | '6 months | ' |
Total number of shares available for purchase | 500 | ' | ' | ' | ' |
Percentage of fair market value of common stock | ' | ' | ' | 85.00% | ' |
Maximum Percentage of total combined voting power a participant is allowed to be granted a right to purchase common stock | ' | ' | ' | 5.00% | ' |
Maximum number of shares allowed to be purchased by single participant | ' | ' | ' | 1,000 | ' |
Number of shares sold under Employee Stock Purchase Plan | ' | 31 | 33 | 66 | 33 |
Cash received under program | ' | 804,000 | 612,000 | 1,474,000 | 612,000 |
Stock options | ' | ' | ' | ' | ' |
Weighted-average assumptions used in the Black-Scholes option pricing model | ' | ' | ' | ' | ' |
Expected stock price volatility (as a percent) | ' | 65.00% | 68.00% | 66.00% | 69.00% |
Risk-free interest rate (as a percent) | ' | 1.39% | 0.63% | 0.86% | 0.81% |
Expected life | ' | '4 years 4 months 13 days | '4 years 6 months 4 days | '4 years 5 months 12 days | '4 years 10 months 13 days |
Expected dividend yield (as a percent) | ' | 0.00% | 0.00% | 0.00% | 0.00% |
Share-based compensation expense additional disclosures | ' | ' | ' | ' | ' |
Weighted-average fair value (as of the date of grant) of the options granted during the period (in dollars per share) | ' | $15.88 | $11.11 | $15.76 | $14.10 |
Pre-tax stock-based compensation expense recorded | ' | 7,300,000 | 4,600,000 | 18,300,000 | 14,400,000 |
After tax stock-based compensation expense | ' | 4,800,000 | 2,900,000 | 12,100,000 | 9,100,000 |
Stock-based compensation expense per diluted share (in dollars per share) | ' | $0.12 | $0.07 | $0.30 | $0.23 |
Stock-based compensation cost related to non-vested equity awards not yet recognized as an expense | ' | 42,800,000 | ' | 42,800,000 | ' |
Weighted-average period over which stock-based compensation cost related to non-vested equity awards is expected to be recognized | ' | ' | ' | '2 years 6 months 29 days | ' |
Number of Options | ' | ' | ' | ' | ' |
Options outstanding at the beginning of the period (in shares) | ' | ' | ' | 3,976 | ' |
Options Granted (in shares) | ' | ' | ' | 612 | ' |
Options Exercised (in shares) | ' | ' | ' | -1,042 | ' |
Options Cancelled (in shares) | ' | ' | ' | -117 | ' |
Options outstanding at the end of the period (in shares) | ' | 3,429 | ' | 3,429 | ' |
Vested or expected to vest (in shares) | ' | 3,253 | ' | 3,253 | ' |
Exercisable (in shares) | ' | 1,994 | ' | 1,994 | ' |
Weighted-Average Exercise Price | ' | ' | ' | ' | ' |
Balance at the beginning of the period (in dollars per share) | ' | ' | ' | $20.88 | ' |
Options Granted (in dollars per share) | ' | ' | ' | $30.20 | ' |
Options Exercised (in dollars per share) | ' | ' | ' | $16.78 | ' |
Options Cancelled (in dollars per share) | ' | ' | ' | $24.96 | ' |
Balance at the end of the period (in dollars per share) | ' | $23.65 | ' | $23.65 | ' |
Vested or expected to vest (in dollars per share) | ' | $23.37 | ' | $23.37 | ' |
Exercisable (in dollars per share) | ' | $20.73 | ' | $20.73 | ' |
Weighted-Average Remaining Contractual Term | ' | ' | ' | ' | ' |
Outstanding | ' | ' | ' | '4 years 6 months 14 days | ' |
Vested or expected to vest | ' | ' | ' | '4 years 5 months 16 days | ' |
Exercisable | ' | ' | ' | '3 years 8 months 23 days | ' |
Aggregate Intrinsic Value | ' | ' | ' | ' | ' |
Outstanding | ' | 49,432,000 | ' | 49,432,000 | ' |
Vested or expected to vest | ' | 47,803,000 | ' | 47,803,000 | ' |
Exercisable | ' | $34,560,000 | ' | $34,560,000 | ' |
Restricted stock | ' | ' | ' | ' | ' |
Number of Awards | ' | ' | ' | ' | ' |
Non-vested at the beginning of the period (in shares) | ' | ' | ' | 866 | ' |
Granted (in shares) | ' | ' | ' | 829 | ' |
Vested (in shares) | ' | ' | ' | -241 | ' |
Forfeited (in shares) | ' | ' | ' | -102 | ' |
Non-vested at the end of the period (in shares) | ' | 1,352 | ' | 1,352 | ' |