Incentive Plans - Summary of Impact of LFI and Other Similar Deferred Compensation Arrangements (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share Based Compensation [Abstract]
Amortization, net of forfeitures	$ 28,310	$ 19,852	$ 41,293	$ 40,751
Change in the fair value of underlying investments	5,753	312	13,106	(2,202)
Total	$ 34,063	$ 20,164	$ 54,399	$ 38,549

Amount of expense recognized from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments), awarded to key employees or individuals. Excludes amount related to plans that cover generally all employees (for example, but not limited to, qualified pension plans).

No definition available.

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Balance Type:	debit
Period Type:	duration