Schedule I - Condensed Statements of Comprehensive (Loss) Income (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2017
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
The impact of an immaterial correction of an error	The parent company only condensed statements of comprehensive (loss) income reflect a correction to record its wholly owned subsidiary’s other comprehensive income (loss), which had previously been omitted for 2016 and 2015. The correction of this immaterial omission did not impact the Company’s consolidated financial statements for any periods presented.