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Share-Based Compensation - Additional Information (Detail) (USD $)
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1 Months Ended | 12 Months Ended | 12 Months Ended | |||||||||||
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Dec. 18, 2013
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Dec. 31, 2013
CompensationPlan
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Dec. 31, 2012
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Dec. 31, 2011
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Dec. 31, 2013
Restricted Stock [Member]
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Dec. 31, 2013
ACM LLC [Member]
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Dec. 31, 2012
ACM LLC [Member]
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Dec. 31, 2013
Stock Plan 2010 and 2013 [Member]
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Dec. 31, 2012
Stock Plan 2010 and 2013 [Member]
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Dec. 31, 2011
Stock Plan 2010 and 2013 [Member]
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Dec. 31, 2013
Stock Plan 2010 and 2013 [Member]
Director [Member]
Restricted Stock [Member]
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Dec. 21, 2013
Stock Plan 2010 and 2013 [Member]
Option 2 [Member]
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Dec. 31, 2013
Employee Stock Purchase Plan [Member]
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Dec. 31, 2013
Employee Stock Purchase Plan [Member]
Maximum [Member]
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| Schedule Of Share Based Compensation Arrangement [Line Items] | ||||||||||||||
| Common Stock, Capital Shares Reserved for Future Issuance | 11,956,570 | 424,594 | ||||||||||||
| Common stock units available to grant | 396,640 | 6,587,390 | ||||||||||||
| Number of share-based employee compensation plans | 2 | |||||||||||||
| Contractual life of granted options | 10 years | |||||||||||||
| Options vesting percentage | 20.00% | 25.00% | ||||||||||||
| Options vesting period | 4 years | 4 years | 4 years | |||||||||||
| 2013 Omnibus Plan settlement, Description | DSUs will be settled in shares of our common stock 90 days after the director ceases to serve as a director. | |||||||||||||
| DSU settlement period | 90 days | |||||||||||||
| Stock options exercised | 121,556 | 0 | ||||||||||||
| Total unrecognized compensation costs related to unvested stock options | $ 900,000 | $ 14,700,000 | ||||||||||||
| Weighted average period related to unvested stock options | 7 years 5 months 16 days | 3 years 10 months 24 days | 2 years 7 months 6 days | |||||||||||
| Total grant date fair value of stock options vested | 300,000 | 4,100,000 | 3,200,000 | 1,600,000 | ||||||||||
| ACM shares Owned | 821,411 | |||||||||||||
| Stock per ACM unit | 0.048413 | |||||||||||||
| Plan Commitment percentage | 90.00% | |||||||||||||
| ACM units granted prior to July1 2006 | 13,800,000 | |||||||||||||
| Cash paid by employee upon vesting of ACM unit | 0 | |||||||||||||
| Common stock units authorized | 396,640 | |||||||||||||
| Distribution of ACM units | 821,346 | 498,000 | ||||||||||||
| Dissolution of ACM, Year | 2014 | |||||||||||||
| Purchase Price of Common Stock, Percent | 15.00% | |||||||||||||
| Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period | 0 | |||||||||||||
| Stock compensation expense | $ 5,621,000 | $ 3,545,000 | $ 1,795,000 | |||||||||||