Fair Value - Presentation of Carrying Values and Fair Values of Certain of Company's Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Assets:
Investments, available-for-sale	$ 135,745	$ 125,085
Other investments	12,087	10,530
Liabilities:
Debentures payable	40,245	40,211
Term loan from principal stockholder	29,747
Carrying Value
Assets:
Investments, available-for-sale	135,745	125,085
Other investments	12,087	10,530
Liabilities:
Debentures payable	40,245	40,211
Term loan from principal stockholder	29,747
Fair Value
Assets:
Investments, available-for-sale	135,745	125,085
Other investments	12,087	10,530
Liabilities:
Debentures payable	20,896	$ 19,606
Term loan from principal stockholder	$ 31,128