Guarantor Financial Information (Narrative) (Details)	Dec. 31, 2019	Dec. 31, 2018
Two Point Nine Percent Senior Notes Due Two Thousand Twenty One [Member] [Member]
Debt instrument, interest rate	2.90%	2.90%
4.250% Senior Notes Due 2013 [Member]
Debt instrument, interest rate	4.25%	4.25%
Three Point Seven Five Percent Senior Notes Due Two Thousand Twenty Eight [Member]
Debt instrument, interest rate	3.75%	3.75%
5.750% Senior Notes Due 2043 [Member]
Debt instrument, interest rate	5.75%	5.75%
Four Point Three Percent Senior Notes Due Two Thousand Forty Eight [Member]
Debt instrument, interest rate	4.30%	4.30%
9.00% Debentures Due 2021 [Member]
Debt instrument, interest rate	9.00%	9.00%
7.20% Debentures Due 2014-2025 [Member]
Debt instrument, interest rate	7.20%	7.20%
6.48% Debentures Due 2025 [Member]
Debt instrument, interest rate	6.48%	6.48%
6.625% Percent Senior Notes Due Two Thousand Twenty [Member]
Debt instrument, interest rate		2.625%
2.625 Percent Notes Due 2020 [Member]
Debt instrument, interest rate	2.625%
3.55% Senior Notes due 2024 [Member]
Debt instrument, interest rate	3.55%	3.55%
4.650% Percent Senior Notes due Twenty Forty Four [Member]
Debt instrument, interest rate	3.50%
Three Point Eight Percent Senior Notes Due Two Thousand Twenty Nine [Member]
Debt instrument, interest rate	3.80%
Four Point Six Five Percent Senior Notes due Twenty Forty Four [Member]
Debt instrument, interest rate	4.65%	4.65%
Four Point Five Percent Senior Notes Due Two Thousand Forty Nine [Member]
Debt instrument, interest rate	4.50%