Stock-Based Employee Compensation Plans - Stock Option Activity under Plans (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Number of Shares
Outstanding, beginning of period (in shares)			838,696	1,257,390
Granted (in shares)		0	379,551	112,828
Exercised (in shares)	(41,780)	(22,252)	(83,158)	(226,564)
Forfeited/Canceled (in shares)			(57,737)	(134,553)
Outstanding, end of period (in shares)	1,077,352	1,009,101	1,077,352	1,009,101
Option Exercisable, end of period (in shares)	576,670	529,284	576,670	529,284
Options Vested, end of period (in shares)	576,670	529,284	576,670	529,284
Weighted Average Exercise Price Per Share
Weighted Average Exercise Price, beginning of period (in dollars per share)			$ 6.20	$ 6.51
Granted (in dollars per share)			6.92	7.09
Exercised (in dollars per share)			4.37	5.54
Forfeited/Canceled (in dollars per share)			8.88	11.56
Weighted Average Exercise Price, end of period (in dollars per share)	$ 6.45	$ 6.12	6.45	6.12
Options Exercisable, end of period (in dollars per share)	6.13	5.80	6.13	5.80
Options Vested, end of period (in dollars per share)	$ 6.07	$ 5.80	$ 6.07	$ 5.80