Equity Incentive Compensation Plans (Range of Exercise Prices) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Stock Options Outstanding, Number of Options	1,387,592
Stock Options Outstanding, Weighted Average Remaining Contractual Life (Years)	4 years 29 days
Stock Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 33.71	$ 30.32	$ 25.87	$ 25.36
Stock Options Outstanding, Aggregate Intrinsic Value (in dollars)	$ 4,681
Stock Options Exercisable, Number of Options	1,239,733
Stock Options Exercisable, Weighted Average Remaining Contractual Life (Years)	3 years 6 months 12 days
Stock Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 31.65
Stock Options Exercisable, Aggregate Intrinsic Value (in dollars)	$ 4,681
Exercise Prices 9.61 to 9.97
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Range of Exercise Prices, Lower Range Limit (in dollars)	$ 9.61
Range of Exercise Prices, Upper Range Limit (in dollars)	$ 9.97
Stock Options Outstanding, Number of Options	43,850
Stock Options Outstanding, Weighted Average Remaining Contractual Life (Years)	11 months 5 days
Stock Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 9.89
Stock Options Exercisable, Number of Options	43,850
Stock Options Exercisable, Weighted Average Remaining Contractual Life (Years)	11 months 5 days
Stock Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 9.89
Exercise Prices 21.58 to 21.77
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Range of Exercise Prices, Lower Range Limit (in dollars)	$ 21.58
Range of Exercise Prices, Upper Range Limit (in dollars)	$ 21.77
Stock Options Outstanding, Number of Options	253,000
Stock Options Outstanding, Weighted Average Remaining Contractual Life (Years)	1 year 10 months 25 days
Stock Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 21.60
Stock Options Exercisable, Number of Options	253,000
Stock Options Exercisable, Weighted Average Remaining Contractual Life (Years)	1 year 10 months 25 days
Stock Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 21.60
Exercise Prices 30.65 to 32.57
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Range of Exercise Prices, Lower Range Limit (in dollars)	$ 30.65
Range of Exercise Prices, Upper Range Limit (in dollars)	$ 32.57
Stock Options Outstanding, Number of Options	639,500
Stock Options Outstanding, Weighted Average Remaining Contractual Life (Years)	3 years 6 months 5 days
Stock Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 31.70
Stock Options Exercisable, Number of Options	639,500
Stock Options Exercisable, Weighted Average Remaining Contractual Life (Years)	3 years 6 months 5 days
Stock Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 31.70
Exercise Prices 38.00 to 53.02
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Range of Exercise Prices, Lower Range Limit (in dollars)	$ 38.00
Range of Exercise Prices, Upper Range Limit (in dollars)	$ 53.02
Stock Options Outstanding, Number of Options	451,242
Stock Options Outstanding, Weighted Average Remaining Contractual Life (Years)	6 years 5 months 6 days
Stock Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 45.66
Stock Options Exercisable, Number of Options	303,383
Stock Options Exercisable, Weighted Average Remaining Contractual Life (Years)	5 years 3 months 23 days
Stock Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 43.05