Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

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

Restricted Stock Unit and Performance Share Transactions

A summary of restricted stock unit and performance share transactions for the year ended December 31, 2018, is shown below:

	Restricted Stock Units		Weighted Average Grant Date Fair Value	Performance Shares		Weighted Average Grant Date Fair Value
Outstanding as of December 31, 2017	572,213		$109.31	1,199,570		$115.33
Granted	141,439		$168.86	274,026		$179.40
Distributed (vested)	(162,144	)		(453,956	)
Cancelled	(34,177	)		(98,934	)
Outstanding as of December 31, 2018 (1)	517,331		$125.30	920,706		$139.56
Vested or expected to vest as of December 31, 2018	517,331			651,244

(1) Outstanding performance shares are reflected at the maximum possible payout that may be earned during the relevant performance periods.