Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated foreign currency translation loss
Balance			$ (122,552)	$ (137,613)
Other comprehensive income (loss) before reclassifications:
Pre-tax			(16,315)	8,600
Tax effect			0	0
Amounts reclassified from accumulated other comprehensive loss to:
Tax effect			0	0
Net current period other comprehensive income (loss)			(16,315)	8,600
Balance	$ (138,867)	$ (129,013)	(138,867)	(129,013)
Accumulated gain (loss) on interest rate swaps
Balance			(674)	(9,331)
Other comprehensive income (loss) before reclassifications:
Pre-tax			14,875	(3,488)
Tax effect	(1,078)	1,542	(3,570)	1,308
Amounts reclassified from accumulated other comprehensive loss to:
Tax effect			(593)	(2,554)
Net current period other comprehensive income	3,778	(581)	13,183	2,076
Balance	12,509	(7,255)	12,509	(7,255)
Total
Balance			(123,226)	(146,944)
Other comprehensive income (loss) before reclassifications:
Pre-tax			(1,440)	5,112
Tax effect			(3,570)	1,308
Amounts reclassified from accumulated other comprehensive loss to:
Tax effect			(593)	(2,554)
Net current period other comprehensive income			(3,132)	10,676
Balance	$ (126,358)	$ (136,268)	(123,226)	(146,944)
Floorplan interest expense (pre-tax)
Amounts reclassified from accumulated other comprehensive loss to:
Interest expense			0	0
Amounts reclassified from accumulated other comprehensive loss to:
Interest expense			2,999	5,656
Amounts reclassified from accumulated other comprehensive loss to:
Pre-tax			2,999	5,656
Other interest expense (pre-tax)
Amounts reclassified from accumulated other comprehensive loss to:
Interest expense			0	0
Amounts reclassified from accumulated other comprehensive loss to:
Interest expense			390	1,154
Amounts reclassified from accumulated other comprehensive loss to:
Pre-tax			390	$ 1,154
Realized gain on swap termination (pre-tax)
Amounts reclassified from accumulated other comprehensive loss to:
Interest expense			0
Amounts reclassified from accumulated other comprehensive loss to:
Interest expense			(918)
Amounts reclassified from accumulated other comprehensive loss to:
Pre-tax			$ (918)