Amount of realized and unrealized gain (loss) on investment.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27405-111563

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.7(c),9(a))
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

Reference 3: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Name:	us-gaap_GainLossOnInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Joint Ventures and Investments - Equity Method Investments (Parenthetical) (Detail) - USD ($) $ in Thousands	1 Months Ended		9 Months Ended
	Sep. 30, 2017	Apr. 30, 2016	Sep. 30, 2017
Schedule Of Equity Method Investments [Line Items]
Pre-tax gain on deconsolidation of joint venture			$ 3,772
Galore Media, Inc. \| Series A Preferred Stock
Schedule Of Equity Method Investments [Line Items]
Shares repurchase	50,050
Shares purchased, value	$ 500
Share repurchase amount received upon execution of agreement	300
Share repurchase remaining amount was received	$ 200		$ 200
Shares repurchase forfeited and surrendered upon execution of agreement		46,067