STOCK-BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2019

Share-based Payment Arrangement [Abstract]

Summary of Additional Information Concerning Restricted Stock Units

The following table summarizes additional information concerning restricted stock units at December 31, 2019:

	Restricted Stock Units		Weighted Average Grant Date Fair Value Per Unit
Unvested as of December 31, 2018	1,477,318		$	17.88
Granted	603,131		20.59
Vested	(433,181	)	18.34
Dividends reinvested	152,329		18.60
Cancelled/forfeited	(61,735	)	18.29
Unvested as of December 31, 2019	1,737,862		$	18.90

Summary of Assumptions Used in Total Stockholder Return-Based Stock Units Valuation

The following are the key assumptions used in this valuation:

	2019		2018		2017
Risk free interest rate	1.57% - 2.54%		2.36% - 2.59%		1.42% - 1.99%
Expected stock price volatility	23.80% - 28.57%		28.57% - 30.02%		28.86% - 30.97%
Expected service period	2.4 - 3.0 years		2.5 - 3.0 years		2.2 - 3.0 years
Expected dividend yield (assuming full reinvestment)	—	%	—	%	—	%