EQUITY COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of equity-based compensation expense, net of assumed forfeitures

Equity-based compensation expense, net of forfeitures is included in the following table:

	For the Year Ended December 31,
	2017		2016		2015
Restricted units	$	54,339	$	21,894	$	14,035
Options	13,848		15,450		16,575
Phantom units	1,524		1,721		1,634
Equity-based compensation expense	$	69,711	$	39,065	$	32,244

Summary of unvested restricted units' activity

The following table presents unvested restricted units’ activity during the year ended December 31, 2017:

	Restricted Units		Weighted Average Grant Date Fair Value Per Unit
Balance - January 1, 2017	8,058,372		$	16.38
Granted	7,999,669		18.60
Vested	(1,843,730	)	16.57
Forfeited	(462,423	)	18.19
Balance - December 31, 2017	13,751,888		$	17.58

Summary of unvested options activity

A summary of unvested options activity during the year ended December 31, 2017 is presented below:

	Options		Weighted Average Exercise Price		Weighted Average Remaining Life (in years)	Aggregate Intrinsic Value
Balance - January 1, 2017	22,232,134		$	18.99	7.35	$	4,586
Granted	—		—		—	—
Exercised	(54,500	)	19.00		—	205
Expired	(523,440	)	19.00		—	—
Forfeited	(1,159,169	)	19.00		—	—
December 31, 2017	20,495,025		$	18.99	6.09	$	20,611
Exercisable at December 31, 2017	7,369,430		$	19.00	5.62	$	7,369

Schedule of weighted average assumptions used for fair value

The fair value of each option granted during each year is measured on the date of the grant using the Black‑Scholes option pricing model and the following weighted average assumptions:

	For the Year Ended December 31,
	2017(2)	2016(2)	2015
Risk-free interest rate	N/A	N/A	1.71% to 1.80%
Weighted average expected dividend yield	N/A	N/A	5.00%
Expected volatility factor(1)	N/A	N/A	35.00% to 36.00%
Expected life in years	N/A	N/A	6.66 to 7.49

(1)   Expected volatility is based on comparable companies using daily stock prices.

(2) There were no new options granted during the years ended December 31, 2017 and 2016.

Summary of unvested Phantom units activity

A summary of unvested phantom units’ activity during the year ended December 31, 2017 is presented below:

	Phantom Units		Weighted Average Grant Date Fair Value Per Unit
Balance - January 1, 2017	266,138		$	19.00
Vested	(87,222	)	19.00
Forfeited	(22,763	)	19.00
December 31, 2017	156,153		$	19.00

Schedule of Adoption of ASU 2016-09

The Company adopted ASU 2016-09 effective January 1, 2016 using a modified retrospective approach and recorded a cumulative-effect adjustment with the following impact to beginning equity:

	Partners' Capital			Non-Controlling Interest in AOG Entities			Redeemable Interest in AOG Entities
Balance at December 31, 2015	$	251,537		$	397,883		$	23,505
Retained earnings	(3,357		)	(5,470		)	(38		)
Paid-in-capital - equity compensation	3,767			6,138			43
Distributions - dividend equivalent	(410		)	(668		)	(5		)
Balance at December 31, 2015 (as adjusted)	$	251,537		$	397,883		$	23,505