Investments - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Measurement Inputs, Disclosure [Line Items]
Amortization period of gains		5 years
Deferred gain on sale of certain merchant banking assets	$ 0	$ 195	$ 195
GCP I
Fair Value, Measurement Inputs, Disclosure [Line Items]
Investment related to noncontrolling interests	100	100
GCP II
Fair Value, Measurement Inputs, Disclosure [Line Items]
Investment related to noncontrolling interests	$ 600	$ 600
GCP III
Fair Value, Measurement Inputs, Disclosure [Line Items]
Sale of capital interests			$ 2,000
Iridium common stock
Fair Value, Measurement Inputs, Disclosure [Line Items]
Sale of common stock (shares)			5,084,016
Average price per share (usd per share)			$ 6.73