Summary of Significant Accounting Policies impact of recently issued accounting standards (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2018		Sep. 29, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2017		Sep. 30, 2017		Jul. 01, 2017		Apr. 01, 2017		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax																	$ 0				$ 2,685
Sales	$ 7,918,182		$ 7,490,445		$ 7,392,528		$ 6,875,613		$ 7,539,449		$ 6,856,108		$ 6,422,226		$ 5,736,780		29,676,768	[1]	$ 26,554,563	[1]	23,487,872	[1]
Cost of sales									6,610,269		6,013,541		5,598,202		4,975,583		25,975,856		23,197,595		20,343,550
Gross profit	975,370		923,778		932,820		868,944		929,180		842,567		824,024		761,197		3,700,912		3,356,968		3,144,322
Selling, general, and administrative expenses																	2,303,051		2,162,045		2,046,910
Depreciation and amortization																	186,384		153,599		159,195
Loss on disposition of businesses, net																	3,604		21,000		0
Restructuring, integration, and other charges																	60,361		74,588		61,391
Total operating expenses																	2,553,400		2,411,232		2,267,496
Operating income	334,380		290,310		286,827		235,995		286,824		235,441		230,446		193,025		1,147,512		945,736		876,826
Equity in earnings of affiliated companies																	(2,332)		3,424		7,573
Gain (loss) on investments, net																	14,166		6,577		(2,896)
Loss on extinguishment of debt													58,800				0		59,545		0
Employee benefit plan expense																	6,870		23,869		20,464
Interest and other financing expense, net																	214,771		165,252		151,312
Income before income taxes																	909,373		693,917		715,519
Provision for income taxes																	187,799		286,541		190,731
Consolidated net income																	721,574		407,376		524,788
Noncontrolling interests																	5,379		5,200		1,973
Net income attributable to shareholders	$ 230,653	[2]	$ 176,533		$ 169,915		$ 139,094		$ 53,653	[2]	$ 134,064		$ 99,722	[3]	$ 114,737		$ 716,195		$ 402,176		$ 522,815
Net income per share:
Basic	$ 2.66	[4]	$ 2.02	[4]	$ 1.94	[4]	$ 1.58	[4]	$ 0.61	[4]	$ 1.52	[4]	$ 1.12	[4]	$ 1.29	[4]	$ 8.19		$ 4.54		$ 5.75
Diluted	$ 2.63	[4]	$ 1.99	[4]	$ 1.92	[4]	$ 1.56	[4]	$ 0.60	[4]	$ 1.50	[4]	$ 1.11	[4]	$ 1.27	[4]	$ 8.10	[5]	$ 4.48	[5]	$ 5.68	[5]
Accounting standards update 2018-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax																	$ 4,116
Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax																	$ 18,238
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Sales									$ 7,633,870		$ 6,953,740		$ 6,465,346		$ 5,759,552				$ 26,812,508		$ 23,825,261
Cost of sales									6,703,742		6,110,382		5,641,380		4,999,665				23,455,169		20,681,062
Gross profit																			3,357,339		3,144,199
Selling, general, and administrative expenses																			2,162,996		2,052,863
Depreciation and amortization																			153,599		159,195
Loss on disposition of businesses, net																			21,000		0
Restructuring, integration, and other charges																			91,294		73,602
Total operating expenses																			2,428,889		2,285,660
Operating income									270,914		235,992		229,822		191,722				928,450		858,539
Equity in earnings of affiliated companies																			3,424		7,573
Gain (loss) on investments, net																			14,231		0
Loss on extinguishment of debt																			59,545		0
Employee benefit plan expense																			0		0
Interest and other financing expense, net																			163,810		150,715
Income before income taxes																			694,288		715,397
Provision for income taxes																			287,126		190,674
Consolidated net income																			407,162		524,723
Noncontrolling interests																			5,200		1,973
Net income attributable to shareholders									$ 53,885		$ 134,630		$ 99,679		$ 113,768				$ 401,962		$ 522,750
Net income per share:
Basic																			$ 4.53		$ 5.75
Diluted																			$ 4.48		$ 5.68
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Sales																			$ (257,945)		$ (337,389)
Cost of sales																			(257,574)		(337,512)
Gross profit																			(371)		123
Selling, general, and administrative expenses																			(951)		(5,953)
Depreciation and amortization																			0		0
Loss on disposition of businesses, net																			0		0
Restructuring, integration, and other charges																			(16,706)		(12,211)
Total operating expenses																			(17,657)		(18,164)
Operating income																			17,286		18,287
Equity in earnings of affiliated companies																			0		0
Gain (loss) on investments, net																			(7,654)		(2,896)
Loss on extinguishment of debt																			0		0
Employee benefit plan expense																			(23,869)		(20,464)
Interest and other financing expense, net																			1,442		597
Income before income taxes																			(371)		122
Provision for income taxes																			(585)		57
Consolidated net income																			214		65
Noncontrolling interests																			0		0
Net income attributable to shareholders																			$ 214		$ 65
Net income per share:
Basic																			$ 10.00		$ 0
Diluted																			$ 0		$ 0

[1] Includes sales related to the United States of $12,157,306, $11,038,930, and $10,137,041 for 2018, 2017, and 2016, respectively.

[2] Net income attributable to shareholders includes a U.S. Tax Act benefit of $28.3 million and expense of $124.7 million during the fourth quarter of 2018 and 2017, respectively.

[3] Net income attributable to shareholders includes a loss on extinguishment of debt of $58.8 million during the second quarter of 2017.

[4] Quarterly net income per share is calculated using the weighted-average shares outstanding during each quarterly period, while net income per share for the full year is calculated using the weighted-average shares outstanding during the year. Therefore, the sum of the net income per share for each of the four quarters may not equal the net income per share for the full year.

[5] Stock-based compensation awards for the issuance of 651 shares, 380 shares, and 766 shares for the years ended December 31, 2018, 2017, and 2016, respectively, were excluded from the computation of net income per share on a diluted basis as their effect was anti-dilutive.