Interim Financial Information (Unaudited) Schedule of Interim Impact of New Accounting Standard (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	$ 10,464,501	$ 9,340,029	$ 8,886,101	$ 8,548,319	$ 10,033,397	$ 8,448,471	$ 8,092,353	$ 7,023,620	$ 37,238,950	$ 33,597,841	$ 24,193,697
Cost of Goods and Services Sold					9,416,536	7,922,390	7,576,762	6,566,532	$ 34,983,051	31,482,220	22,891,770
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues					11,092,529	9,135,728	8,882,691	7,664,063		36,775,011	26,234,876
Cost of Goods and Services Sold					$ 10,475,668	$ 8,609,647	$ 8,367,100	$ 7,206,975		$ 34,659,390	$ 24,932,949