Stock-Based Compensation (Details 2) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Vested and exercisable | Minimum
Exercise Price
Exercise Price (in dollars per share)	$ 20.17	$ 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)	$ 20.17	$ 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)	(71)
Forfeited (in shares)	(14)
Vested and exercisable at the end of the period (in shares)	681	681
Unvested at the end of the period (in shares)	246	232
Total outstanding at the end of the period (in shares)	927	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)	$ 18.78
Forfeited (in dollars per share)	$ 23.67
Vested and exercisable at the end of the period (in dollars per share)	$ 23.42	$ 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)	$ 23.21	$ 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)	$ 160,000
Total outstanding at the beginning of the period (in dollars)	160,000
Granted (in dollars)	78,000
Exercised (in dollars)	305,000	524,000	1,122,000
Forfeited (in dollars)	2,000
Vested and exercisable at the end of the period (in dollars)	271,000	160,000
Unvested at the end of the period (in dollars)	77,000
Total outstanding at the end of the period (in dollars)	348,000	160,000
Vested during year (in dollars)	$ 28,000
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	$ 5.04	$ 5.31
Exercised (in dollars per share)	$ 3.85
Forfeited (in dollars per share)	$ 5.21
Vested and exercisable at the end of the period (in dollars per share)	$ 5.33	$ 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)	$ 5.15	$ 5.19
Vested during year (in dollars per share)	$ 5.33
Weighted Average Remaining Contractual Life
Vested and exercisable	3 years 6 months	3 years 10 months 24 days
Unvested	7 years 10 months 24 days	7 years 8 months 12 days
Total outstanding	4 years 8 months 12 days	4 years 10 months 24 days