Stock-Based Compensation (Details 2) (USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Vested and exercisable | Minimum
Exercise price
Exercise price (in dollars per share)	$ 20.17	$ 20.17
Vested and exercisable | Maximum
Exercise price
Exercise price (in dollars per share)	$ 26.83	$ 26.83
Unvested | Minimum
Exercise price
Exercise price (in dollars per share)	$ 21.03	$ 21.03
Unvested | Maximum
Exercise price
Exercise price (in dollars per share)	$ 24.87	$ 26.83
Outstanding | Minimum
Exercise price
Exercise price (in dollars per share)	$ 20.17	$ 20.17
Outstanding | Maximum
Exercise price
Exercise price (in dollars per share)	$ 26.83	$ 26.83
Granted
Exercise price
Exercise price (in dollars per share)	$ 22.89
Exercised | Minimum
Exercise price
Exercise price (in dollars per share)	$ 20.17
Exercised | Maximum
Exercise price
Exercise price (in dollars per share)	$ 26.83
Forfeited | Minimum
Exercise price
Exercise price (in dollars per share)	$ 21.03
Forfeited | Maximum
Exercise price
Exercise price (in dollars per share)	$ 23.76
Vested during the year | Minimum
Exercise price
Exercise price (in dollars per share)	$ 21.03
Vested during the year | Maximum
Exercise price
Exercise price (in dollars per share)	$ 24.87
Options and SARs
Options and SARs
Vested and exercisable at the beginning of the period (in shares)	681
Unvested at the beginning of the period (in shares)	246
Total outstanding at the beginning of the period (in shares)	927
Granted (in shares)	54
Exercised (in shares)	(117)
Forfeited (in shares)	(4)
Vested and exercisable at the end of the period (in shares)	642	681
Unvested at the end of the period (in shares)	218	246
Total outstanding at the end of the period (in shares)	860	927
Vested during year (in shares)	79
Weighted average exercise price
Vested and exercisable at the beginning of the period (in dollars per share)	$ 23.42
Unvested at the beginning of the period (in dollars per share)	$ 22.62
Total outstanding at the beginning of the period (in dollars per share)	$ 23.21
Granted (in dollars per share)	$ 22.89
Exercised (in dollars per share)	$ 21.49
Forfeited (in dollars per share)	$ 22.78
Vested and exercisable at the end of the period (in dollars per share)	$ 23.66	$ 23.42
Unvested at the end of the period (in dollars per share)	$ 22.70	$ 22.62
Total outstanding at the end of the period (in dollars per share)	$ 23.42	$ 23.21
Vested during year (in dollars per share)	$ 22.56
Aggregate intrinsic value
Vested and exercisable at the beginning of the period (in dollars)	$ 271
Unvested at the beginning of the period (in dollars)	77
Total outstanding at the beginning of the period (in dollars)	348
Granted (in dollars)	292
Exercised (in dollars)	557
Forfeited (in dollars)	19
Vested and exercisable at the end of the period (in dollars)	2,997	271
Unvested at the end of the period (in dollars)	1,228	77
Total outstanding at the end of the period (in dollars)	4,225	348
Vested during year (in dollars)	$ 458
Weighted average fair value
Vested and exercisable at the beginning of the period (in dollars per share)	$ 5.33
Unvested at the beginning of the period (in dollars per share)	$ 4.67
Total outstanding at the beginning of the period (in dollars per share)	$ 5.15
Granted (in dollars per share)	$ 3.61
Exercised (in dollars per share)	$ 4.74
Forfeited (in dollars per share)	$ 4.88
Vested and exercisable at the end of the period (in dollars per share)	$ 5.38	$ 5.33
Unvested at the end of the period (in dollars per share)	$ 4.36	$ 4.67
Total outstanding at the end of the period (in dollars per share)	$ 5.12	$ 5.15
Vested during year (in dollars per share)	$ 4.81
Weighted average remaining contractual life
Vested and exercisable	3 years 4 months 24 days	3 years 6 months
Unvested	7 years 10 months 24 days	7 years 10 months 24 days
Total outstanding	4 years 7 months 6 days	4 years 8 months 12 days