Earnings Per Common Share (Impact Of Company's Stock Price On Assuming Dilution Calculation For The Subordinated Convertible Notes) (Details) (Subordinated Convertible Notes Due 2029 [Member], USD $)	12 Months Ended
	Dec. 31, 2012
Share price	$ 36.75
$36.75 [Member]
Share price	$ 36.75
Incremental common shares attributable to contingently issuable shares	0
$38.75 [Member]
Share price	$ 38.75
Incremental common shares attributable to contingently issuable shares	603,152
$40.75 [Member]
Share price	$ 40.75
Incremental common shares attributable to contingently issuable shares	1,147,099
$42.75 [Member]
Share price	$ 42.75
Incremental common shares attributable to contingently issuable shares	1,640,151
$44.75 [Member]
Share price	$ 44.75
Incremental common shares attributable to contingently issuable shares	2,089,131
Total Treasury Method Incremental Shares [Member] | $36.75 [Member]
Incremental common shares attributable to contingently issuable shares	0	[1]
Total Treasury Method Incremental Shares [Member] | $38.75 [Member]
Incremental common shares attributable to contingently issuable shares	603,152	[1]
Total Treasury Method Incremental Shares [Member] | $40.75 [Member]
Incremental common shares attributable to contingently issuable shares	1,147,099	[1]
Total Treasury Method Incremental Shares [Member] | $42.75 [Member]
Incremental common shares attributable to contingently issuable shares	1,640,151	[1]
Total Treasury Method Incremental Shares [Member] | $44.75 [Member]
Incremental common shares attributable to contingently issuable shares	2,089,131	[1]

[1] Represents the number of incremental shares that must be included in the calculation of fully diluted shares under U.S. GAAP.