Stock-Based Compensation Plans Shared-Based Compensation Activity (Details) (USD $)	6 Months Ended
	Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Total Options and Non-Option Equity Instruments, Outstanding [Roll Forward]
Total outstanding, number	588,856
Total granted, number	166,720
Total exercised, number	192,950
Total canceled, number	667
Total outstanding, number	561,959
Total exercisable, number	293,068
2004 LTIP [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Outstanding, number	188
Granted, number	0
Exercised, number	(188)
Canceled, number	0
Outstanding, number	0
Exercisable, number	0
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, price	0.01
Granted, price	0.00
Exercised, price	0.01
Canceled, price	0.00
Outstanding, price	0.00
Exercisable, price	0.00
2004 LTIP [Member] | Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, number	41,077
Granted, number	0
Exercised, number	(15,701)
Canceled, number	0
Outstanding, number	25,376
Exercisable, number	25,376
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, price	35.08
Granted, price	0.00
Exercised, price	34.75
Canceled, price	0.00
Outstanding, price	35.28
Exercisable, price	35.28
2005 LTIP [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Outstanding, number	3,053
Granted, number	0
Exercised, number	0
Canceled, number	0
Outstanding, number	3,053
Exercisable, number	3,053
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, price	0.01
Granted, price	0.00
Exercised, price	0.00
Canceled, price	0.00
Outstanding, price	0.01
Exercisable, price	0.01
2005 Directors' Plan [Member] | Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, number	7,500
Granted, number	0
Exercised, number	(5,500)
Canceled, number	0
Outstanding, number	2,000
Exercisable, number	2,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, price	27.03
Granted, price	0.00
Exercised, price	27.03
Canceled, price	0.00
Outstanding, price	27.03
Exercisable, price	27.03
2007 LTIP [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Outstanding, number	78,509	[1]
Granted, number	0	[1]
Exercised, number	(28,671)	[1]
Canceled, number	(167)	[1]
Outstanding, number	49,671	[1]
Exercisable, number	26,410	[1]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, price	0.01	[1]
Granted, price	0.00	[1]
Exercised, price	0.01	[1]
Canceled, price	0.01	[1]
Outstanding, price	0.01	[1]
Exercisable, price	0.01	[1]
2007 LTIP [Member] | Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, number	274,034	[1]
Granted, number	0	[1]
Exercised, number	(47,858)	[1]
Canceled, number	0	[1]
Outstanding, number	226,176	[1]
Exercisable, number	226,176	[1]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, price	25.71	[1]
Granted, price	0.00	[1]
Exercised, price	26.09	[1]
Canceled, price	0.00	[1]
Outstanding, price	25.63	[1]
Exercisable, price	25.63	[1]
2007 LTIP [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Outstanding, number	11,271	[1]
Granted, number	0	[1]
Exercised, number	(2,818)	[1]
Canceled, number	0	[1]
Outstanding, number	8,453	[1]
Exercisable, number	8,453	[1]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, price	0.01	[1]
Granted, price	0.00	[1]
Exercised, price	0.01	[1]
Canceled, price	0.00	[1]
Outstanding, price	0.01	[1]
Exercisable, price	0.01	[1]
2010 LTIP [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Outstanding, number	137,532	[1]
Granted, number	81,468	[1]
Exercised, number	(72,132)	[1]
Canceled, number	(500)	[1]
Outstanding, number	146,368	[1]
Exercisable, number	900	[1]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, price	0.01	[1]
Granted, price	0.01	[1]
Exercised, price	0.01	[1]
Canceled, price	0.01	[1]
Outstanding, price	0.01	[1]
Exercisable, price	0.01	[1]
2010 LTIP [Member] | Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, number	7,500	[1]
Granted, number	0	[1]
Exercised, number	0	[1]
Canceled, number	0	[1]
Outstanding, number	7,500	[1]
Exercisable, number	0	[1]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, price	32.78	[1]
Granted, price	0.00	[1]
Exercised, price	0.00	[1]
Canceled, price	0.00	[1]
Outstanding, price	32.78	[1]
Exercisable, price	0.00	[1]
2010 LTIP [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Outstanding, number	28,192	[1]
Granted, number	85,252	[1]
Exercised, number	(20,082)	[1]
Canceled, number	0	[1]
Outstanding, number	93,362	[1]
Exercisable, number	700	[1]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, price	0.01	[1]
Granted, price	0.01	[1]
Exercised, price	0.01	[1]
Canceled, price	0.00	[1]
Outstanding, price	0.01	[1]
Exercisable, price	0.01	[1]

[1] The 2007 and 2010 LTIPs are for officers, employees and non-employee directors.