Summary of Significant Accounting Policies and Practices - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Significant Accounting Policies [Line Items]
Maturity period of highly liquid investments	Three months or less
Percentage of subsidiaries owned	100.00%	100.00%	100.00%
Joint Venture [Member]
Significant Accounting Policies [Line Items]
Percentage of subsidiaries owned	49.00%
RFK [Member]
Significant Accounting Policies [Line Items]
Percentage of subsidiaries owned	99.70%