Share-Based Compensation (Details 4) (USD $)	12 Months Ended
	Dec. 31, 2012
Range One [Member]
Summary of information concerning stock options outstanding and exercisable
Range of Exercise Prices, upper limit	$ 19.20
Options Outstanding, Shares	247,867
Options Outstanding, Weighted-Average Remaining Contractual Life	7 years
Options vested, shares	$ 19.20
Options Exercisable, Shares	166,740
Options Exercisable, Weighted-Average Exercise Price	$ 19.20
Range Two [Member]
Summary of information concerning stock options outstanding and exercisable
Range of Exercise Prices, upper limit	$ 19.57
Options Outstanding, Shares	43,796
Options Outstanding, Weighted-Average Remaining Contractual Life	3 months 18 days
Options vested, shares	$ 19.57
Options Exercisable, Shares	43,796
Options Exercisable, Weighted-Average Exercise Price	$ 19.57
Range Three [Member]
Summary of information concerning stock options outstanding and exercisable
Range of Exercise Prices, lower limit	$ 23.28
Range of Exercise Prices, upper limit	$ 31.92
Options Outstanding, Shares	29,433
Options Outstanding, Weighted-Average Remaining Contractual Life	1 year 1 month 6 days
Options vested, shares	$ 29.43
Options Exercisable, Shares	27,433
Options Exercisable, Weighted-Average Exercise Price	$ 29.76
Range Four [Member]
Summary of information concerning stock options outstanding and exercisable
Range of Exercise Prices, lower limit	$ 33.81
Range of Exercise Prices, upper limit	$ 38.44
Options Outstanding, Shares	42,800
Options Outstanding, Weighted-Average Remaining Contractual Life	1 year 8 months 12 days
Options vested, shares	$ 35.86
Options Exercisable, Shares	38,040
Options Exercisable, Weighted-Average Exercise Price	$ 36.12
Range Five [Member]
Summary of information concerning stock options outstanding and exercisable
Range of Exercise Prices, lower limit	$ 19.20
Range of Exercise Prices, upper limit	$ 38.44
Options Outstanding, Shares	363,896
Options Outstanding, Weighted-Average Remaining Contractual Life	5 years 1 month 6 days
Options vested, shares	$ 22.03
Options Exercisable, Shares	276,009
Options Exercisable, Weighted-Average Exercise Price	$ 22.64