Fair Value - Presentation of Carrying Values and Fair Values of Certain of Company's Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets:
Investments, available-for-sale	$ 131,582	$ 125,085
Other investments	11,256	10,530
Liabilities:
Debentures payable	40,256	40,211
Term loan from principal stockholder	29,753
Carrying Value
Assets:
Investments, available-for-sale	131,582	125,085
Other investments	11,256	10,530
Liabilities:
Debentures payable	40,256	40,211
Term loan from principal stockholder	29,753
Fair Value
Assets:
Investments, available-for-sale	131,582	125,085
Other investments	11,256	10,530
Liabilities:
Debentures payable	20,275	$ 19,606
Term loan from principal stockholder	$ 28,504