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Goodwill - Additional Information (Detail) (USD $)	6 Months Ended	12 Months Ended
Goodwill - Additional Information (Detail) (USD $)	Jun. 30, 2013	Dec. 31, 2013	Dec. 31, 2014	Apr. 17, 2013
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill	$ 71,400,000us-gaap_Goodwill	$ 94,781,000us-gaap_Goodwill	$ 94,781,000us-gaap_Goodwill
Reduction of goodwill related to Merganser	400,000us-gaap_GoodwillPeriodIncreaseDecrease
Impairment Charge		23,987,000us-gaap_GoodwillImpairmentLoss
Merganser
Goodwill and Intangible Assets Disclosure [Line Items]
Reduction of goodwill related to Merganser		32,400,000
Impairment Charge		24,000,000
Reduction of goodwill from sale of assets		8,400,000
CreXus
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill				71,350,000
Goodwill		$ 71,800,000