Debt (Tables)

12 Months Ended

Dec. 31, 2016

Short-term Debt [Line Items]

Schedule of Long-term Debt Instruments [Text Block]

Long-term debt consists of the following at December 31:

	2016		2015
Revolving credit facility	$	—	$	72,000
Asset securitization program	460,000		75,000
6.875% senior debentures, due 2018	199,348		198,886
3.00% notes, due 2018	299,013		298,197
6.00% notes, due 2020	299,183		298,932
5.125% notes, due 2021	248,843		248,566
3.50% notes, due 2022	345,776		345,061
4.50% notes, due 2023	296,646		296,194
4.00% notes, due 2025	344,625		344,092
7.50% senior debentures, due 2027	198,514		198,366
Interest rate swaps designated as fair value hedges	152		711
Other obligations with various interest rates and due dates	4,234		4,570
	$	2,696,334	$	2,380,575

Schedule of Fair Value of Debt [Text Block]

The estimated fair market value at December 31, using quoted market prices, is as follows:

	2016		2015
6.875% senior debentures, due 2018	$	212,500	$	218,000
3.00% notes, due 2018	303,500		303,000
6.00% notes, due 2020	325,500		330,000
5.125% notes, due 2021	265,500		267,500
3.50% notes, due 2022	349,500		343,000
4.50% notes, due 2023	305,500		309,000
4.00% notes, due 2025	345,000		336,000
7.50% senior debentures, due 2027	238,000		238,000