Common Stock (Tables)

12 Months Ended

Dec. 31, 2017

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

Schedule of stock option activity

The following table presents information associated with options as of December 31, 2017 and 2016, and for the years ended December 31, 2017, 2016 and 2015:

	2017		2016		2015
Intrinsic value of options outstanding as of December 31	$	80	$	43
Intrinsic value of options exercisable as of December 31	72		43
Intrinsic value of options exercised	6		4		7
Weighted-average grant date fair value per option	$	84.60	$	—	$	—

A summary of the transactions within the Company’s stock option plans follows (shares in thousands):

	Shares		Weighted-Average Exercise Price
Outstanding at December 31, 2016	507		21.37
Granted	105		60.89
Exercised	(63	)	39.72
Canceled	—		—
Outstanding at December 31, 2017	549		26.80
Exercisable at December 31, 2017	480		$	22.04

Summary of restricted stock units activity

A summary of RSUs granted follows (RSUs in thousands):

	Year Ended December 31,
	2017		2016		2015
RSUs granted	809		901		463
Weighted-average grant date price per unit	$	130.96	$	60.55	$	86.84

A summary of RSU activity for the year ended December 31, 2017 follows (RSUs in thousands):

	Stock Units		Weighted-Average Grant Date Fair Value
Nonvested as of December 31, 2016	751		$	71.29
Granted	809		130.96
Vested	(782	)	110.37
Forfeited	(22	)	93.13
Nonvested as of December 31, 2017	756		$	94.07