Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of intangible assets, excluding goodwill, acquired at the acquisition date.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Total loss recognized during the period from the impairment of goodwill plus the loss recognized in the period resulting from the impairment of the carrying amount of intangible assets, other than goodwill.

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Goodwill and Intangible Assets - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Jul. 01, 2013
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 17,311,000us-gaap_Goodwill	$ 17,311,000us-gaap_Goodwill	$ 17,311,000us-gaap_Goodwill	$ 17,311,000us-gaap_Goodwill
Goodwill and intangible assets impairment	0	0
Weighted average useful life			5 years	6 years
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization period, in years			1 year
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization period, in years			9 years
Knight [Member]
Finite-Lived Intangible Assets [Line Items]
Identifiable intangible assets					155,425,000
Goodwill					$ 12,666,000