Share-Based Compensation - Stock Option Activity under Stock Option Plans (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Number of Shares
Beginning balance (in shares)	442,012
Granted (in shares)	0	0
Exercised (in shares)	(6,700)
Cancelled (in shares)	(49,500)
Ending balance (in shares)	385,812
Vested and Expected to Vest (in shares)	385,812
Exercisable (in shares)	385,812
Weighted-Average Exercise Price
Beginning balance (in dollars per share)	$ 19.99
Granted (in dollars per share)
Exercised (in dollars per share)	$ 10.80
Cancelled (in dollars per share)	25.14
Ending balance (in dollars per share)	19.49
Vested and Expected to Vest (in dollars per share)	19.49
Exercisable (in dollars per share)	$ 19.49
Weighted Average Remaining Contractual Term (in Years)
Outstanding	3 years 2 months 22 days
Vested and Expected to Vest	3 years 2 months 22 days
Exercisable	3 years 2 months 22 days
Aggregate Intrinsic Value
Outstanding	$ 1,992,120
Vested and Expected to Vest	1,992,120
Exercisable	$ 1,992,120