Share-Based Compensation - Stock Option Activity under Stock Option Plans (Details) (USD $)	9 Months Ended
	Sep. 30, 2014
Number of Shares
Beginning balance (in shares)	958,786
Granted (in shares)	13,500
Exercised (in shares)	(38,650)
Cancelled (in shares)	(193,106)
Ending balance (in shares)	740,530
Vested and Expected to Vest (in shares)	740,530
Exercisable (in shares)	718,030
Weighted-Average Exercise Price
Beginning balance (in dollars per share)	$ 21.32
Granted (in dollars per share)	$ 21.65
Exercised (in dollars per share)	$ 11.64
Cancelled (in dollars per share)	$ 24.42
Ending balance (in dollars per share)	$ 20.99
Vested and Expected to Vest (in dollars per share)	$ 20.99
Exercisable (in dollars per share)	$ 21.05
Weighted Average Remaining Contractual Term
Outstanding	3 years 3 months 26 days
Vested and Expected to Vest	3 years 3 months 26 days
Exercisable	3 years 1 month 21 days
Aggregate Intrinsic Value
Outstanding	$ 1,929,297
Vested and Expected to Vest	1,929,297
Exercisable	$ 1,885,287