Equity Incentive Plans (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Summary of the activity of stock option awards
Options outstanding, Beginning Balance, Shares	1,198
Options outstanding, Beginning Balance, Wtd. Avg. Exercise Price	$ 18.92
Options outstanding, Beginning Balance, Wtd. Avg., Remaining Contractual Term	6 years 7 months 24 days	6 years 10 months 6 days
Options outstanding, Beginning Balance, Aggregate Intrinsic Value	$ 11,090
Options granted, Shares	0
Options granted, Wtd. Avg. Exercise Price	$ 0.00
Options exercised, Shares	(293)
Options exercised, Wtd. Avg. Exercise Price	$ 16.85
Options forfeited/canceled/expired, Shares	(21)
Options forfeited/canceled/expired, Wtd. Avg. Exercise Price	$ 21.43
Options outstanding, Ending Balance, Shares	884	1,198
Options outstanding, Ending Balance, Wtd. Avg. Exercise Price	$ 19.68	$ 18.92
Options outstanding, Ending Balance, Wtd. Avg., Remaining Contractual Term	6 years 7 months 24 days	6 years 10 months 6 days
Options outstanding, Ending Balance, Aggregate Intrinsic Value	11,994	11,090
Options vested and expected to vest at June 30, 2013, Shares	861
Options vested and expected to vest at June 30, 2013, Wtd. Avg. Exercise Price	$ 19.63
Options vested and expected to vest at June 30, Wtd. Avg., Remaining Contractual Term	6 years 7 months 13 days
Options vested and expected to vest at June 30, 2013, Aggregate Intrinsic Value	11,727
Options exercisable at June 30, 2013 Shares	545
Options exercisable at June 30, 2013, Wtd. Avg. Exercise Price	$ 18.92
Options exercisable at June 30, 2013, Wtd. Avg. Remaining Contractual Term	6 years 2 months 1 day
Options exercisable at June 30, 2013, Aggregate Intrinsic Value	$ 7,819