Stock Compensation Plans (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share Based Compensation Plans (Additional Textual) [Abstract]
Expected life - years	6 years	6 years	6 years
Total intrinsic value of options exercised	$ 25,200,000	$ 28,200,000	$ 26,000,000
Recognized Stock-based compensation expense before tax	12,100,000	10,800,000	9,400,000
Amount accrued for shares settling in cash	6,200,000
Share Based Compensation Plans (Textual) [Abstract]
Percentage of vest increments of Stock option awards	25.00%
Vest in percentage increments of restricted shares	25.00%
Recognized Stock-based compensation expense after tax	7,600,000	6,800,000	5,900,000
Recognized Stock-based compensation expense diluted share	$ 0.08	$ 0.07	$ 0.06
Period for trailing daily stock prices used in comparison to calculate dividend yield	12 months
Estimated forfeitures	4.00%
Net cash proceeds from the exercise of stock options	13,100,000	13,800,000	16,600,000
Income tax benefits	8,900,000	8,100,000	7,200,000
Restricted deferred shares and deferred dividend credits	397,052
Shares distributed	221,542	249,569	302,924
Number of shares available for future grants for all plans	7,562,958
Unrecognized compensation expense is expected to be recognized over a total weighted average period	2 years
Stock Options [Member]
Share Based Compensation Plans (Additional Textual) [Abstract]
Expected life - years	10 years
Performance unit component under its long term incentive plan [Member]
Share Based Compensation Plans (Additional Textual) [Abstract]
Company performance measured by two metrics over performance period	3 years
Canceled or expired, Number of Shares	160,668
Cash value of performance unit	100
Restricted deferred shares and deferred dividend awarded [Member]
Share Based Compensation Plans (Additional Textual) [Abstract]
Shares awarded	111,640	161,905	246,890
Performance Restricted Stock [Member]
Share Based Compensation Plans (Additional Textual) [Abstract]
Shares awarded			34,756
Common stock shares outstanding relating to performance units granted		156,183
Restricted Stock [Member]
Share Based Compensation Plans (Additional Textual) [Abstract]
Canceled or expired, Number of Shares	17,110
Shares awarded	111,640
Unrecognized Compensation expense related to stock option awards, restricted shares and deferred shares	28,100,000
Recognized Stock-based compensation expense before tax	$ 6,500,000	$ 7,200,000	$ 7,500,000
Vesting period	3 years
Strategic Performance Shares [Member]
Share Based Compensation Plans (Additional Textual) [Abstract]
Shares awarded	260,740
Shares expected to settle in cash	243,580
Shares expected to settle in shares	17,160
Strategic Shares [Member]
Share Based Compensation Plans (Additional Textual) [Abstract]
Shares awarded	121,080
Shares expected to settle in cash	65,400
Shares expected to settle in shares	55,680