Other Income (Loss), Net (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Income and Expense [Line Items]
Loss on mark-to-market of holdings in trading securities									$ (493)
Loss on impairment									(216)	$ (2,360)
Gain on sale of business										424	$ 2,914
Other										254	57
Other income (loss), net	$ (120)	$ (379)	$ (89)	$ 249	$ 64	$ (2,405)	$ 659	$ 0	(339)	(1,682)	217
Dabo [Member]
Other Income and Expense [Line Items]
Loss on impairment											(2,356)
Penn Mezzanine Assets [Member]
Other Income and Expense [Line Items]
Gain (loss) on extinguishment of debt									399	$ (2,400)
Convertible Senior Debentures due 2018 [Member]
Other Income and Expense [Line Items]
Gain (loss) on extinguishment of debt									$ (29)
Legacy Private Equity Funds [Member]
Other Income and Expense [Line Items]
Loss on impairment											$ (398)