Acquisitions - Additional Information (Details) shares in Millions					3 Months Ended		4 Months Ended	6 Months Ended
	Mar. 21, 2017 USD ($)	Mar. 06, 2017 USD ($)	Feb. 03, 2017 USD ($)	Nov. 30, 2016 USD ($) employee country	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Mar. 21, 2017 USD ($) shares	Jun. 30, 2017 USD ($)	Apr. 05, 2017 USD ($)	Mar. 14, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 14, 2016 USD ($)	Nov. 30, 2016 € / shares	Nov. 17, 2016 USD ($)	Aug. 01, 2016 USD ($)	May 05, 2016 USD ($)
Business Acquisition [Line Items]
Escrow deposits					$ 0			$ 0			$ 744,748,000
Adjustment to preliminary purchase allocation								79,855,000
Goodwill					2,343,608,000			2,343,608,000			2,078,765,000
Acquired indefinite-lived intangible assets					668,900,000			668,900,000
Customer Relationships
Business Acquisition [Line Items]
Acquired indefinite-lived intangible assets					307,100,000			$ 307,100,000
Intangible assets, weighted average useful life (years)								20 years
Noncompete Agreements
Business Acquisition [Line Items]
Intangible assets, weighted average useful life (years)								5 years
Intellectual Property
Business Acquisition [Line Items]
Acquired indefinite-lived intangible assets					5,000,000			$ 5,000,000
Intangible assets, weighted average useful life (years)								20 years
Trade Names
Business Acquisition [Line Items]
Acquired indefinite-lived intangible assets					355,100,000			$ 355,100,000
Faiveley Transport
Business Acquisition [Line Items]
Annual sales of Faiveley				$ 1,200,000,000
Number of employees (more than) | employee				5,700
Number of countries Faiveley operates in | country				24
Purchase price per share (in euros per share) | € / shares													€ 100
Outstanding share capital acquired (as a percent)													51.00%
Percentage of voting interests in Faiveley (as a percent)	100.00%	22.00%	27.00%				100.00%						49.00%
Share conversion ratio													1.1538
Additional share capital acquired (as a percent)		21.00%	27.00%
Cash payment for acquisition	$ 17,500,000	$ 303,200,000	$ 411,800,000				$ 944,300,000
Equity issued in acquisition		$ 300,000	$ 25,200,000				$ 560,200,000
Cumulative share capital acquired (as a percent)	100.00%	99.00%	78.00%				100.00%
Cumulative voting rights acquired (as a percent)	100.00%	98.00%	76.00%				100.00%
Business combination, consideration transferred							$ 1,736,100,000
Equity issued in acquisition (in shares) | shares							6.6
Debt assumed in acquisition							$ 409,900,000
Cash acquired in acquisition							178,300,000
Escrow deposits											$ 744,700,000
Acquisition of noncontrolling interest						$ 8,900,000
Adjustment to current liabilities acquired								51,500,000
Accounts receivable	$ 445,164,000						445,164,000
Current liabilities	805,728,000						805,728,000
Adjustment to other noncurrent assets								23,400,000
Adjustment to preliminary purchase allocation								68,600,000
Accrued share based compensation acquired in acquisition					25,900,000			25,900,000
Revenue reported by acquired entity					282,700,000			557,400,000
Goodwill	$ 1,256,855,000						$ 1,256,855,000
Faiveley Transport | Restatement Adjustment | Fair Value of Receivables
Business Acquisition [Line Items]
Accounts receivable					2,800,000			2,800,000
Faiveley Transport | Restatement Adjustment | Fair Value of Current Liabilities
Business Acquisition [Line Items]
Current liabilities					36,200,000			36,200,000
Faiveley Transport | Restatement Adjustment | Fair Value of Assets Acquired and Liabilities Assumed
Business Acquisition [Line Items]
Accounts receivable					64,300,000			64,300,000
Current liabilities						$ 64,300,000
Faiveley Transport | Minimum
Business Acquisition [Line Items]
Percentage of business acquisition consideration payable in cash (as a percent)													25.00%
Faiveley Transport | Maximum
Business Acquisition [Line Items]
Percentage of business acquisition consideration payable in cash (as a percent)													45.00%
Acquisitions other than Faiveley
Business Acquisition [Line Items]
Escrow deposits					$ 38,400,000			$ 38,400,000
TTC
Business Acquisition [Line Items]
Purchase price, net of cash acquired									$ 32,511,000
Goodwill									21,122,000
Goodwill tax deduction									$ 21,100,000.0
ATP
Business Acquisition [Line Items]
Purchase price, net of cash acquired										$ 65,254,000
Goodwill										41,036,000
Goodwill tax deduction										$ 0
Workhorse
Business Acquisition [Line Items]
Purchase price, net of cash acquired												$ 43,827,000
Goodwill												$ 24,373,000
Goodwill deductible for taxes (as a percent)												37.80%
Precision Turbo
Business Acquisition [Line Items]
Purchase price, net of cash acquired														$ 13,826,000
Goodwill														3,959,000
Goodwill tax deduction														$ 3,900,000
Unitrac
Business Acquisition [Line Items]
Purchase price, net of cash acquired																$ 14,771,000
Goodwill																2,442,000
Goodwill tax deduction																$ 1,400,000
Gerken
Business Acquisition [Line Items]
Purchase price, net of cash acquired															$ 62,847,000
Goodwill															17,470,000
Goodwill tax deduction															$ 0