Summary of Significant Accounting Policies (Changes In Warranty And Safety Recall Liability) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance, beginning of period	$ 79,482	$ 74,217	$ 69,250
Warranties issued during the period	57,834	60,215	59,259
Settlements made during the period	(82,554)	(99,298)	(96,529)
Recalls and changes to pre-existing warranty liabilities	39,438	44,348	42,237
Balance, end of period	$ 94,200	$ 79,482	$ 74,217