Interim Financial Information - Impact of Applying Topic 606 on the Consolidated Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	$ 2,889,058	$ 3,012,292	$ 8,692,546	$ 8,203,316
Cost of sales	2,453,957	2,580,872	7,399,519	6,983,482
Selling, general and administrative expenses	316,771	328,327	949,210	916,674
Provision for income taxes	9,587	17,262	38,666	57,076
Net income	34,778	29,881	127,054	102,953
Parts and service sales
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	354,501	343,193	1,062,145	994,522
Cost of sales	162,927	158,036	488,637	458,144
Finance, insurance and other, net
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	116,084	$ 110,993	343,462	$ 314,297
Balances Without Adoption of Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Selling, general and administrative expenses	316,640		948,991
Provision for income taxes	8,490		37,771
Net income	31,278		124,085
Balances Without Adoption of Topic 606 \| Parts and service sales
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	353,588		1,061,160
Cost of sales	162,601		488,412
Balances Without Adoption of Topic 606 \| Finance, insurance and other, net
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	111,943		340,139
ASU 2014-09 \| Adjustment due to Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Selling, general and administrative expenses	131		219
Provision for income taxes	1,097		895
Net income	3,500		2,969
ASU 2014-09 \| Adjustment due to Topic 606 \| Parts and service sales
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	913		985
Cost of sales	326		225
ASU 2014-09 \| Adjustment due to Topic 606 \| Finance, insurance and other, net
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	$ 4,141		$ 3,323

The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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