Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2015

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

Summary of stock option activity

A summary of stock option activity in accordance with the Company’s equity incentive plans as of June 30, 2015 and 2014, and changes for the six-month periods then ended, follows:

	SHARES		WEIGHTED- AVERAGE EXERCISE PRICE		WEIGHTED- AVERAGE REMAINING CONTRACTUAL LIFE (in years)	AGGREGATE INTRINSIC VALUE (in thousands)
Options outstanding at January 1, 2014	2,326,201		$	27.02	2.3
Exercised	(539,733	)	29.24
Forfeited	(15,473	)	21.57
Options outstanding at June 30, 2014	1,770,995		$	26.39	2.4	$	30,216
Available for future grant	3,348,345
Total shares reserved at June 30, 2014	5,119,340
Options exercisable at June 30, 2014	1,544,332		$	27.49	2.0	$	25,571
Options outstanding at January 1, 2015	1,385,497		$	23.30	2.2
Exercised	(424,684	)	20.67
Forfeited	(36,667	)	47.63
Options outstanding at June 30, 2015	924,146		$	23.55	2.2	$	23,666
Available for future grant	3,516,458
Total shares reserved at June 30, 2015	4,440,604
Options exercisable at June 30, 2015	917,479		$	23.50	2.2	$	23,561

Summary of activity that relates to the Company's restricted stock unit awards

The following table summarizes activity that relates to the Company’s restricted stock unit awards:

	2015		2014
Restricted stock units at January 1	368,084		539,106
Shares awarded	170,994		131,597
Shares vested	(231,969	)	(298,791	)
Shares forfeited	(11,082	)	(3,828	)
Restricted stock units at June 30	296,027		368,084