Fair Value - Presentation of Carrying Values and Fair Values of Certain of Company's Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Assets:
Investments, available-for-sale	$ 136,998	$ 125,085
Other investments	11,578	10,530
Liabilities:
Debentures payable	40,107	40,211
Term loan from principal stockholder	29,740
Carrying Value
Assets:
Investments, available-for-sale	136,998	125,085
Other investments	11,578	10,530
Liabilities:
Debentures payable	40,107	40,211
Term loan from principal stockholder	29,740
Fair Value
Assets:
Investments, available-for-sale	136,998	125,085
Other investments	11,578	10,530
Liabilities:
Debentures payable	20,764	$ 19,606
Term loan from principal stockholder	$ 30,000