Incentive Plans - Summary of Impact of LFI and Other Similar Deferred Compensation Arrangements (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share Based Compensation [Abstract]
Amortization, net of forfeitures	$ 23,325	$ 19,145	$ 85,469	$ 71,274
Change in the fair value of underlying investments	1,764	3,647	22,118	1,712
Total	$ 25,089	$ 22,792	$ 107,587	$ 72,986

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