Long-Term Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement, Noncash Expense [Abstract]

Performance Award Valuation Assumptions

The fair values were determined by a lattice-binomial option-pricing model based on Monte Carlo simulations using the following assumptions:

	Year Ended December 31, 2020		Year Ended December 31, 2019		Year Ended December 31, 2018
Expected dividend yield	2.22	%	3.02	%	2.67	%
Expected volatility - range used	16.25% - 17.56%		18.53% - 19.72%		15.83% - 17.87%
Expected volatility - weighted average	16.97	%	19.10	%	17.02	%
Risk-free interest rate	1.63% - 1.68%		2.45% - 2.57%		1.57% - 2.04%

Summary of Performance Award Transactions

Performance Award transactions for the year ended December 31, 2020 are summarized as follows:

	Performance Units	Weighted Average Grant Date Fair Value		Performance RLP Units	Weighted Average Grant Date Fair Value
Outstanding at December 31, 2019	380,722	$	12.89	156,702	$	12.45
Issued	59,263	$	20.65	322,477	$	20.65
Forfeited	(5,681)	$	13.67	—	$	—
Vested	(178,211)	$	12.62	—	$	—
Outstanding at December 31, 2020	256,093	$	14.86	479,179	$	17.97

Summary of Service Award Transactions

Service Award transactions for the year ended December 31, 2020 are summarized as follows:

	Service Units	Weighted Average Grant Date Fair Value		Service RLP Units	Weighted Average Grant Date Fair Value
Outstanding at December 31, 2019	296,371	$	30.56	110,640	$	33.64
Issued	80,387	$	43.61	119,596	$	42.94
Forfeited	(4,009)	$	33.86	(1,967)	$	35.58
Vested	(160,829)	$	29.37	(43,700)	$	33.73
Outstanding at December 31, 2020	211,920	$	36.35	184,569	$	39.62