Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Collected on sold receivables	$ 9,051	$ 6,407
Increase to earnings reinvested in the business	1,438,823		$ 1,414,485
Increase to deferred tax assets	10,980		7,885
(Decrease) to prepaid expense and other current assets	(45,023)		(43,206)
(Decrease) to deferred tax liabilities	(17,722)		$ (18,724)
ASU 2016-15 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Collected on sold receivables	9,051	$ 6,407
ASU 2016-16 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase to earnings reinvested in the business	400
Increase to deferred tax assets	3,000
(Decrease) to prepaid expense and other current assets	(3,700)
(Decrease) to deferred tax liabilities	$ (1,100)