Summary of Stock Option Activity (Parenthetical) (Detail)	3 Months Ended
	Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding amount of stock appreciation right units	2,804,730
Exercisable amount of stock appreciation right units	1,567,775
Maximum | Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum percentage of stock appreciation right units	75.00%