Summary of Changes in Financial Liabilities Measured at Fair Value for Which Level III Inputs Were Used (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial liabilities at fair value	$ 3,678,874		$ 3,521,609
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial liabilities at fair value	0
Changes in unrealized (gains) losses included in earnings related to liabilities	$ 0	$ 0