Short-Term Borrowings and Long-Term Debt (Schedule Related to the Classification of Debt Interest Rate) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fixed Rate [Member]
Debt Instrument [Line Items]
Weighted average rate	1.42%	1.05%
Matures through	2036	2036
Fixed Rate [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate	2.83%	2.83%
Fixed Rate [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate	0.95%	0.54%
Fixed Rate Convertible [Member]
Debt Instrument [Line Items]
Weighted average rate	3.47%	3.47%
Matures through	2018	2018
Fixed Rate Convertible [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate	3.47%	3.47%
Fixed Rate Convertible [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate	3.47%	3.47%
Variable Rate [Member]
Debt Instrument [Line Items]
Weighted average rate	4.00%	4.00%
Matures through	2020	2020
Variable Rate [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate	4.00%	4.00%
Variable Rate [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate	4.00%	4.00%