Stock-Based Compensation - Share Option Activity (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Total fair value of shares vested	$ 400,000	$ 300,000	$ 200,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	312,000
Exercised (in shares)	(57,725)		0
Forfeited or expired (in shares)	(6,625)
Outstanding, end of period (in shares)	247,650	312,000
Exercisable (in shares)	70,900
Vested or Expected to Vest (in shares)	238,932
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, weighted-average exercise price, beginning of period (in dollars per share)	$ 9.33
Exercised, weighted-average exercise price (in dollars per share)	$ 8.16
Forfeited or expired, weighted-average exercise price (in dollars per share)	$ 9.74
Outstanding, weighted-average exercise price, end of period (in dollars per share)	$ 9.59	$ 9.33
Exercisable, weighted-average exercise price (in dollars per share)	$ 9.29
Vested or Expected to Vest, weighted-average exercise price (in dollars per share)	$ 9.56
Outstanding, average remaining contractual term	8 years	8 years 10 months 24 days
Exercisable, average remaining contractual term	7 years 10 months 24 days
Vested or Expected to Vest, average remaining contractual term	8 years
Outstanding, aggregate intrinsic value	2,015,000	1,946,000
Exercisable, aggregate intrinsic value	598,000
Vested or expected to vest, aggregate intrinsic value	1,951,000
Granted (in shares)	0
Granted, weighted-average exercise price (in dollars per share)		$ 5.73	$ 4.06
Total intrinsic value of share options exercised	$ 700,000	$ 200,000