Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2018

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of Nonvested Restricted Stock Units Activity

	Shares subject to restriction (thousands)		Weighted average grant date fair value
Nonvested at December 31, 2017	1,593		$	38.86
Granted	625		$	52.64
Vested	(486	)	$	41.05
Forfeited	(7	)	$	49.48
Nonvested at March 31, 2018	1,725		$	43.26
Granted	68		$	50.86
Vested	(68	)	$	51.11
Forfeited	(142	)	$	45.68
Nonvested at June 30, 2018	1,583		$	43.03
Forfeited	(27	)	$	43.09
Nonvested at September 30, 2018	1,556		$	43.03

Schedule of Share-based Compensation, Performance Shares Award Unvested Activity

	Number of shares (thousands)		Weighted average grant date fair value
Nonvested at December 31, 2017	355		$	39.42
Granted	175		$	52.64
Nonvested at March 31, 2018	530		$	43.79
Granted	95		$	50.20
Forfeited	(144	)	$	45.82
Nonvested at June 30, 2018	481		$	44.45
Forfeited	(2	)	$	47.43
Nonvested at September 30, 2018	479		$	44.43