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Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)
In Thousands, unless otherwise specified |
6 Months Ended | 6 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
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Jun. 30, 2013
Segment
Unit
|
Jun. 30, 2012
Unit
|
Jun. 30, 2013
Minimum [Member]
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Jun. 30, 2013
Maximum [Member]
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Jun. 30, 2013
Class A Common Stock [Member]
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Jun. 26, 2013
Class A Common Stock [Member]
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Jun. 30, 2013
Class B Common Stock [Member]
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Jun. 30, 2013
Class B Common Stock [Member]
SLP [Member]
|
Jun. 30, 2013
Leasehold Improvements [Member]
|
Jun. 30, 2013
Other Fixed Assets [Member]
Minimum [Member]
|
Jun. 30, 2013
Other Fixed Assets [Member]
Maximum [Member]
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| Summary Of Significant Accounting Policies [Line Items] | |||||||||||
| Ownership percentage in a subsidiary | 43.00% | 43.00% | |||||||||
| Number of operating segment | 1 | ||||||||||
| Cash equivalents, maximum maturity period | 90 days | ||||||||||
| Equity method investments, unrealized intercompany profit(loss) not eliminated amount | $ 0 | ||||||||||
| Property, plant and equipment, useful life | 10 years | 3 years | 7 years | ||||||||
| Number of reporting unit | 1 | 1 | |||||||||
| Identifiable finite-lived intangible assets, useful life | 3 years | 20 years | |||||||||
| Common stock voting rights | 1 vote per share | 1 vote per share | |||||||||
| Class of share exchangeable to another class | One share of Class A common stock | One share of Class A common stock | |||||||||