Stockholders' Equity and Equity Compensation (Tables)

3 Months Ended

Mar. 31, 2018

Equity [Abstract]

Summary of all stock award activity

A summary of the stock award activity is as follows:

	Quarter Ended March 31, 2018
	Stock Awards		Weighted Average Award Date Fair Value
Outstanding at December 31, 2017	1,428,878		$	21.53
Restricted stock units awarded	245,886		24.12
Performance stock units awarded	219,943		23.25
Restricted stock units distributed	(275,384	)	17.29
Performance stock units distributed	(296,909	)	21.55
Restricted stock units forfeited	(12,207	)	19.73
Performance stock units forfeited	(11,801	)	25.83
Outstanding at March 31, 2018	1,298,406		$	23.19

Summary of all deferred stock unit activity

A summary of deferred stock unit activity is as follows:

	Quarter Ended March 31, 2018
	Deferred Stock Units		Weighted Average Award Date Fair Value
Outstanding at December 31, 2017	269,977		$	20.14
Awarded	1,900		25.40
Distributed	(4,568	)	22.33
Outstanding at March 31, 2018	267,309		$	20.14

Financial data for stock option exercises

Financial data for stock option exercises are summarized as follows (in thousands):

	Quarter Ended March 31,
	2018		2017
Aggregate intrinsic value of outstanding stock options	$	253	$	444
Aggregate intrinsic value of exercisable stock options	253		444