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Equity Incentive Plans - Additional Information (Detail) (USD $)
In Millions, except Share data, unless otherwise specified
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12 Months Ended |
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Dec. 31, 2013
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Dec. 31, 2012
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Dec. 31, 2011
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Total unrecognized compensation expense employee stock option plans |
$ 3.0 |
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Minimum [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Stock options vesting period |
1 year |
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Maximum [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Stock options vesting period |
3 years |
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Stock Options [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Stock-based compensation expense related to employee stock option plans |
4.4 |
1.6 |
0.7 |
| Weighted average period for unrecognized compensation expense related to grants of stock options |
1 year 2 months 12 days |
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Stock Options [Member] | Minimum [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Stock options vesting period |
4 years |
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Stock Options [Member] | Maximum [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Stock options vesting period |
5 years |
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Restricted Stock And Restricted Stock Units [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Performance-based restricted stock and restricted stock units, eliminated minimum vesting period under amended 2004 plan |
3 years |
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| Stock-based compensation expense related to employee stock option plans |
0.4 |
1.0 |
1.6 |
| Weighted average period for unrecognized compensation expense related to grants of stock options |
6 months |
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| Total unrecognized compensation expense related to grants of restricted stock and restricted stock units |
0.1 |
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| Shares vested related to grants of restricted stock and restricted stock |
$ 0.8 |
$ 1.3 |
$ 1.3 |
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2004 Plan [Member] | Class A common stock [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Common stock shares authorized under 2000 plan and 2004 plan |
10,000,000 |
10,000,000 |
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2004 Plan [Member] | Stock Options [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Contractual term of stock options |
10 years |
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2000 Plan [Member] | Class A common stock [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Common stock shares authorized under 2000 plan and 2004 plan |
11,500,000 |
11,500,000 |
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2000 Plan [Member] | Stock Options [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Contractual term of stock options |
10 years |
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