Financing (Senior Notes) (Narrative) (Details) $ in Thousands		9 Months Ended
May 17, 2018 USD ($) d Rate	Sep. 30, 2018 USD ($) d Rate
Financing
Unsecured senior notes description		The Company has issued a cumulative $3.2 billion aggregate principal amount of unsecured senior notes, which are due between 2021 and 2028, with UMB as trustee. Interest on the senior notes, ranging from 3.550% to 4.875%, is payable semi-annually and is computed on the basis of a 360-day year.
Debt instrument covenant description		Each of the senior notes is subject to certain customary covenants, with which the Company complied as of September 30, 2018.
Senior notes [Member]
Financing
Aggregate principle of unsecured senior notes \| $		$ 3,200,000
Number of days in annual interest calculation period \| d		360
Senior notes [Member] \| $500 million, 4.350% Senior Notes due 2028 [Member]
Financing
Senior notes maturity, year	2028	2028
Interest rate of senior notes	4.35%	4.35%
Number of days in annual interest calculation period \| d	360
Issuance date of senior notes	May 17, 2018
Face amount of senior notes \| $	$ 500,000	$ 500,000
Percentage of face value of debt instrument	99.732%
Minimum [Member] \| Senior notes [Member]
Financing
Senior notes maturity, year		2021
Interest rate of senior notes		3.55%
Maximum [Member] \| Senior notes [Member]
Financing
Senior notes maturity, year		2028
Interest rate of senior notes		4.875%

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Identification of the lender and information about a contractual promise to repay a short-term or long-term obligation, which includes borrowings under lines of credit, notes payable, commercial paper, bonds payable, debentures, and other contractual obligations for payment. This may include rationale for entering into the arrangement, significant terms of the arrangement, which may include amount, repayment terms, priority, collateral required, debt covenants, borrowing capacity, call features, participation rights, conversion provisions, sinking-fund requirements, voting rights, basis for conversion if convertible and remarketing provisions. The description may be provided for individual debt instruments, rational groupings of debt instruments, or by debt in total.

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