Stock-Based Compensation (Details 2) (USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Vested and exercisable | Minimum
Exercise Price
Exercise Price (in dollars per share)	$ 18.62	$ 18.62
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)	$ 26.83	$ 26.83
Outstanding | Minimum
Exercise Price
Exercise Price (in dollars per share)	$ 18.62	$ 18.62
Outstanding | Maximum
Exercise Price
Exercise Price (in dollars per share)	$ 26.83	$ 26.83
Granted | Minimum
Exercise Price
Exercise Price (in dollars per share)	$ 22.86
Granted | Maximum
Exercise Price
Exercise Price (in dollars per share)	$ 23.58
Exercised | Minimum
Exercise Price
Exercise Price (in dollars per share)	$ 18.62
Exercised | Maximum
Exercise Price
Exercise Price (in dollars per share)	$ 23.37
Forfeited | Minimum
Exercise Price
Exercise Price (in dollars per share)	$ 20.71
Forfeited | Maximum
Exercise Price
Exercise Price (in dollars per share)	$ 26.83
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)	$ 26.83
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)	232
Total outstanding at the beginning of the period (in shares)	913
Granted (in shares)	99
Exercised (in shares)	(45)
Forfeited (in shares)	(11)
Vested and exercisable at the end of the period (in shares)	709	681
Unvested at the end of the period (in shares)	247	232
Total outstanding at the end of the period (in shares)	956	913
Vested during year (in shares)	80
Weighted Average Exercise Price
Vested and exercisable at the beginning of the period (in dollars per share)	$ 22.94
Unvested at the beginning of the period (in dollars per share)	$ 22.80
Total outstanding at the beginning of the period (in dollars per share)	$ 22.90
Granted (in dollars per share)	$ 22.87
Exercised (in dollars per share)	$ 18.82
Forfeited (in dollars per share)	$ 23.55
Vested and exercisable at the end of the period (in dollars per share)	$ 23.25	$ 22.94
Unvested at the end of the period (in dollars per share)	$ 22.62	$ 22.80
Total outstanding at the end of the period (in dollars per share)	$ 23.09	$ 22.90
Vested during year (in dollars per share)	$ 23.45
Aggregate Intrinsic Value
Vested and exercisable at the beginning of the period (in dollars)	$ 160
Total outstanding at the beginning of the period (in dollars)	160
Granted (in dollars)	78
Exercised (in dollars)	216
Forfeited (in dollars)	6
Vested and exercisable at the end of the period (in dollars)	752	160
Unvested at the end of the period (in dollars)	264
Total outstanding at the end of the period (in dollars)	1,016	160
Vested during year (in dollars)	$ 75
Weighted Average Fair Value
Vested and exercisable at the beginning of the period (in dollars per share)	$ 5.18
Unvested at the beginning of the period (in dollars per share)	$ 5.22
Total outstanding at the beginning of the period (in dollars per share)	$ 5.19
Granted (in dollars per share)	$ 3.93
Exercised (in dollars per share)	$ 3.86
Forfeited (in dollars per share)	$ 5.18
Vested and exercisable at the end of the period (in dollars per share)	$ 5.29	$ 5.18
Unvested at the end of the period (in dollars per share)	$ 4.67	$ 5.22
Total outstanding at the end of the period (in dollars per share)	$ 5.13	$ 5.19
Vested during year (in dollars per share)	$ 5.33
Weighted Average Remaining Contractual Life
Vested and exercisable	3 years 8 months 12 days	3 years 10 months 24 days
Unvested	8 years 2 months 12 days	7 years 8 months 12 days
Total outstanding	4 years 9 months 18 days	4 years 10 months 24 days