Supplemental Guarantor Information (Statement Of Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net cash provided by (used in) operating activities	$ 663,077	$ 68,270	$ (337,590)
Cash flows from investing activities:
Capital expenditures	(32,051)	(39,295)	(45,440)
Investment in unconsolidated subsidiaries	(23,037)	(14,539)	(454)
Cash used for business acquisition	0	(430,458)	0
Other investing activities, net	4,846	13,100	11,330
Net cash used in investing activities	(50,242)	(471,192)	(34,564)
Cash flows from financing activities:
Financial Services borrowings, net	106,183	63,744	127,636
Proceeds from debt issuance	0	1,995,937	498,087
Repayments of debt	(134,747)	(986,919)	(239,193)
Borrowings under revolving credit facility	2,720,000	619,000	125,000
Repayments under revolving credit facility	(2,720,000)	(619,000)	(125,000)
Stock option exercises	27,720	5,845	10,535
Share repurchases	(916,323)	(603,206)	(442,738)
Dividends paid	(112,748)	(124,666)	(115,958)
Intercompany activities, net	0	0	0
Net cash provided by (used in) financing activities	(1,029,915)	350,735	(161,631)
Net increase (decrease)	(417,080)	(52,187)	(533,785)
Cash, cash equivalents, and restricted cash at beginning of period	723,248	775,435	1,309,220
Cash, cash equivalents, and restricted cash at end of period	306,168	723,248	775,435
Parent Company [Member]
Net cash provided by (used in) operating activities	309,757	256,722	185,946
Cash flows from investing activities:
Capital expenditures	0	0	0
Investment in unconsolidated subsidiaries	0	0	0
Cash used for business acquisition		0
Other investing activities, net	0	0	0
Net cash used in investing activities	0	0	0
Cash flows from financing activities:
Financial Services borrowings, net	0	0	0
Proceeds from debt issuance		1,991,937	498,087
Repayments of debt	(123,000)	(965,245)	(237,995)
Borrowings under revolving credit facility	2,720,000	619,000	125,000
Repayments under revolving credit facility	(2,720,000)	(619,000)	(125,000)
Stock option exercises	27,720	5,845	10,535
Share repurchases	(916,323)	(603,206)	(442,738)
Dividends paid	(112,748)	(124,666)	(115,958)
Intercompany activities, net	814,594	(561,387)	90,959
Net cash provided by (used in) financing activities	(309,757)	(256,722)	(197,110)
Net increase (decrease)	0	0	(11,164)
Cash, cash equivalents, and restricted cash at beginning of period	0	0	11,164
Cash, cash equivalents, and restricted cash at end of period	0	0	0
Guarantor Subsidiaries [Member]
Net cash provided by (used in) operating activities	328,163	(102,054)	(430,940)
Cash flows from investing activities:
Capital expenditures	(25,432)	(36,297)	(41,857)
Investment in unconsolidated subsidiaries	(23,037)	(14,539)	(454)
Cash used for business acquisition		(430,458)
Other investing activities, net	5,778	11,189	2,391
Net cash used in investing activities	(42,691)	(470,105)	(39,920)
Cash flows from financing activities:
Financial Services borrowings, net	0	0	0
Proceeds from debt issuance		4,000	0
Repayments of debt	(10,301)	(21,235)	(1,198)
Borrowings under revolving credit facility	0	0	0
Repayments under revolving credit facility	0	0	0
Stock option exercises	0	0	0
Share repurchases	0	0	0
Dividends paid	0	0	0
Intercompany activities, net	(728,555)	541,703	(27,886)
Net cash provided by (used in) financing activities	(738,856)	524,468	(29,084)
Net increase (decrease)	(453,384)	(47,691)	(499,944)
Cash, cash equivalents, and restricted cash at beginning of period	611,185	658,876	1,158,820
Cash, cash equivalents, and restricted cash at end of period	157,801	611,185	658,876
Non-Guarantor Subsidiaries [Member]
Net cash provided by (used in) operating activities	25,157	(86,398)	(92,596)
Cash flows from investing activities:
Capital expenditures	(6,619)	(2,998)	(3,583)
Investment in unconsolidated subsidiaries	0	0	0
Cash used for business acquisition		0
Other investing activities, net	(932)	1,911	8,939
Net cash used in investing activities	(7,551)	(1,087)	5,356
Cash flows from financing activities:
Financial Services borrowings, net	106,183	63,744	127,636
Proceeds from debt issuance		0	0
Repayments of debt	(1,446)	(439)	0
Borrowings under revolving credit facility	0	0	0
Repayments under revolving credit facility	0	0	0
Stock option exercises	0	0	0
Share repurchases	0	0	0
Dividends paid	0	0	0
Intercompany activities, net	(86,039)	19,684	(63,073)
Net cash provided by (used in) financing activities	18,698	82,989	64,563
Net increase (decrease)	36,304	(4,496)	(22,677)
Cash, cash equivalents, and restricted cash at beginning of period	112,063	116,559	139,236
Cash, cash equivalents, and restricted cash at end of period	148,367	112,063	116,559
Eliminating Entries [Member]
Net cash provided by (used in) operating activities	0	0	0
Cash flows from investing activities:
Capital expenditures	0	0	0
Investment in unconsolidated subsidiaries	0	0	0
Cash used for business acquisition		0
Other investing activities, net	0	0	0
Net cash used in investing activities	0	0	0
Cash flows from financing activities:
Financial Services borrowings, net	0	0	0
Proceeds from debt issuance		0	0
Repayments of debt	0	0	0
Borrowings under revolving credit facility	0	0	0
Repayments under revolving credit facility	0	0	0
Stock option exercises	0	0	0
Share repurchases	0	0	0
Dividends paid	0	0	0
Intercompany activities, net	0	0	0
Net cash provided by (used in) financing activities	0	0	0
Net increase (decrease)	0	0	0
Cash, cash equivalents, and restricted cash at beginning of period	0	0	0
Cash, cash equivalents, and restricted cash at end of period	$ 0	$ 0	$ 0