Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated foreign currency translation loss
Balance			$ (122,552)	$ (137,613)
Other comprehensive (loss) income before reclassifications:
Pre-tax			(22,223)	16,998
Tax effect			0	0
Amounts reclassified from accumulated other comprehensive loss to:
Tax effect			0	0
Net current period other comprehensive (loss) income			(22,223)	16,998
Tax effects reclassified from accumulated other comprehensive loss			0
Balance	$ (144,775)	$ (120,615)	(144,775)	(120,615)
Accumulated (loss) gain on interest rate swaps
Balance			(674)	(9,331)
Other comprehensive income (loss) before reclassifications:
Pre-tax			18,401	(3,899)
Tax effect	(846)	154	(4,416)	1,462
Amounts reclassified from accumulated other comprehensive loss to:
Tax effect			(860)	(3,581)
Net current period other comprehensive income	3,522	1,454	16,705	3,531
Tax effects reclassified from accumulated other comprehensive loss			(150)
Balance	15,881	(5,800)	15,881	(5,800)
Total
Balance			(123,226)	(146,944)
Other comprehensive income (loss) before reclassifications:
Pre-tax			(3,822)	13,099
Tax effect			(4,416)	1,462
Amounts reclassified from accumulated other comprehensive loss to:
Tax effect			(860)	(3,581)
Net current period other comprehensive income			(5,518)	20,529
Tax effects reclassified from accumulated other comprehensive loss			(150)
Balance	$ (128,894)	$ (126,415)	(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			4,021	7,995
Amounts reclassified from accumulated other comprehensive loss to:
Pre-tax			4,021	7,995
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			477	1,554
Amounts reclassified from accumulated other comprehensive loss to:
Pre-tax			477	$ 1,554
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)