Share-Based Compensation - Stock Option Activity under Stock Option Plans (Details) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Number of Shares
Beginning balance (in shares)	906,636
Granted (in shares)	9,000
Exercised (in shares)	(6,000)
Cancelled (in shares)	(8,471)
Ending balance (in shares)	901,165
Vested and Expected to Vest at June 30, 2013 (in shares)	901,165
Exercisable at June 30, 2013 (in shares)	863,865
Weighted-Average Exercise Price
Beginning balance (in dollars per share)	$ 21.58
Granted (in dollars per share)	$ 15.32
Exercised (in dollars per share)	$ 7.37
Cancelled (in dollars per share)	$ 24.69
Ending balance (in dollars per share)	$ 21.66
Vested and Expected to Vest at June 30, 2013 (in dollars per share)	$ 21.66
Exercisable at June 30, 2013 (in dollars per share)	$ 22.06
Weighted Average Remaining Contractual Term
Outstanding at June 30, 2013	4 years 0 months 11 days
Vested and Expected to Vest at June 30, 2013	3 years 7 months 6 days
Exercisable at June 30, 2013	3 years 9 months 15 days
Aggregate Intrinsic Value
Outstanding at June 30, 2013	$ 1,471
Vested and Expected to Vest at June 30, 2013	1,471
Exercisable at June 30, 2013	$ 1,292