STOCK-BASED COMPENSATION (Tables)

6 Months Ended

Jun. 30, 2018

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

Summary of restricted stock awards

The following table summarizes information about restricted stock awards for the six months ended June 30, 2018:

Restricted Stock	Number of Shares		Weighted Average Grant-Date Fair Value
Balance at January 1, 2018	604,933		$	54.23
Granted	200,688		$	52.92
Vested	(152,283	)	$	54.65
Forfeited	(17,136	)	$	53.63
Balance at June 30, 2018	636,202		$	53.73

Summary of performance stock awards

The following table summarizes information about performance stock awards for the six months ended June 30, 2018:

Performance Stock	Number of Shares		Weighted Average Grant-Date Fair Value
Balance at January 1, 2018	190,129		$	55.63
Vested	(8,696	)	$	54.26
Forfeited	(12,889	)	$	55.09
Balance at June 30, 2018	168,544		$	55.75