Purchase Price Allocations for Acquisitions (Details) $ in Thousands, € in Millions	3 Months Ended		6 Months Ended		12 Months Ended			15 Months Ended
	Mar. 31, 2016 USD ($)	Mar. 31, 2016 EUR (€)	Jun. 30, 2018 USD ($)	Jun. 30, 2018 EUR (€)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2017 USD ($)	Mar. 31, 2016 EUR (€)	Dec. 31, 2015 USD ($)
Business Acquisition
Receivables					$ 163,997	$ 73,782		$ 73,782
Receivable reserves					(3,736)	(7,032)		(7,032)
Inventories (3)					394,259	150,342		150,342
Prepaid expenses and other current assets					12,821	(295)		(295)
Property, plant and equipment					277,003	41,039		41,039
Goodwill					4,381,458	3,536,511	$ 3,054,769	3,536,511		$ 2,319,246
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net						314,817		314,817
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill					320,414	181,216		181,216
Other assets					16,662	3,257		3,257
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities					(83,415)	(65,087)		(65,087)
Current liabilities assumed					(366,904)	(111,484)		(111,484)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt					(84,800)	(33,586)		(33,586)
Other noncurrent liabilities assumed					(91,130)	(1,917)		(1,917)
Consolidation, Less Than Wholly Owned Subsidiary, Non Controlling Interest Acquired, Value					(44,110)	0
Contingent consideration liabilities					(3,107)	(6,234)		(6,234)
Other purchase price obligations					(2,461)	(5,074)		(5,074)
Stock Issued During Period, Value, Acquisitions					(251,334)	0	0
Notes issued					(11,347)	(20,187)		(20,187)
Settlement of pre-existing balances					0	242		242
Gains on bargain purchases					(2,418)	(3,870)	(8,207)
Settlement of other purchase price obligations (non-interest bearing)					1,711	3,159
Cash used in acquisitions, net of cash acquired					1,214,995	513,088	1,349,339
Defined Benefit Plan, Benefit Obligation, Business Combination					79,211	938
Warn Industries [Member]
Business Acquisition
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles					5,000
Inventory step-up adjustment - acquisition related						4,000
2017 Acquisitions Excluding Warn [Member]
Business Acquisition
Business Acquisition Cost Of Acquired Entity Other Purchase Price Obligations Non Interest Bearing, Post Purchase Adjustment					(4,000)
2017 acquisitions and adjustments to 2016 acquisitions [Member]
Business Acquisition
Notes issued						(20,000)		(20,000)
Cash used in acquisitions, net of cash acquired						510,000
Stahlgruber [Member]
Business Acquisition
Receivables					144,826
Receivable reserves					(2,818)
Inventories (3)					380,238
Prepaid expenses and other current assets					10,970
Property, plant and equipment					271,292
Goodwill					908,253
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill					285,255
Other assets					16,625
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities					(78,130)
Current liabilities assumed					(346,788)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt					(79,925)
Other noncurrent liabilities assumed					(80,824)
Consolidation, Less Than Wholly Owned Subsidiary, Non Controlling Interest Acquired, Value					(44,110)
Contingent consideration liabilities					0
Other purchase price obligations					(6,084)
Stock Issued During Period, Value, Acquisitions					(251,334)
Notes issued					0
Settlement of pre-existing balances					0
Gains on bargain purchases					0
Settlement of other purchase price obligations (non-interest bearing)					0
Cash used in acquisitions, net of cash acquired			$ 1,100,000	€ 1,000	1,127,446
Defined Benefit Plan, Benefit Obligation, Business Combination					79,000
All 2018 Acquisitions and adjustments to 2017 acquisitions excluding Stahlgruber
Business Acquisition
Receivables					19,171
Receivable reserves					(918)
Inventories (3)					14,021
Prepaid expenses and other current assets					1,851
Property, plant and equipment					5,711
Goodwill					64,637
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill					35,159
Other assets					37
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities					(5,285)
Current liabilities assumed					(20,116)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt					(4,875)
Other noncurrent liabilities assumed					(10,306)
Consolidation, Less Than Wholly Owned Subsidiary, Non Controlling Interest Acquired, Value					0
Contingent consideration liabilities					(3,107)
Other purchase price obligations					3,623
Stock Issued During Period, Value, Acquisitions					0
Notes issued					(11,347)
Settlement of pre-existing balances					0
Gains on bargain purchases					(2,418)
Settlement of other purchase price obligations (non-interest bearing)					1,711
Cash used in acquisitions, net of cash acquired					87,549
All 2018 and 2017 Acquisitions [Member]
Business Acquisition
Goodwill					$ 972,890
Rhiag
Business Acquisition
Settlement of pre-existing balances	$ 1,000								€ 1
Cash used in acquisitions, net of cash acquired	$ 601,000	€ 534
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment						(6,000)
PGW
Business Acquisition
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment						(3,000)
Andrew Page
Business Acquisition
Gains on bargain purchases						(2,000)	$ (8,000)	$ (10,000)
Gain on bargain purchase						$ (2,000)