Fair Value - Presentation of Carrying Values and Fair Values of Certain Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Assets:
Investments, available-for-sale	$ 117,431	$ 117,212
Other investments	10,140	9,994
Carrying Value
Assets:
Investments, available-for-sale	117,431	117,212
Other investments	10,140	9,994
Liabilities:
Debentures payable	40,313	40,302
Term loan from principal stockholder	29,786	29,779
Fair Value
Assets:
Investments, available-for-sale	117,431	117,212
Other investments	10,140	9,994
Liabilities:
Debentures payable	13,443	11,488
Term loan from principal stockholder	$ 17,210	$ 15,000