Segment Reporting (Details) $ in Thousands		3 Months Ended			6 Months Ended			12 Months Ended
		Jun. 30, 2018 USD ($) segment	Jun. 30, 2017 USD ($) segment		Jun. 30, 2018 USD ($) segment	Jun. 30, 2017 USD ($) segment		Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Segment Reporting Information [Line Items]
Total revenues		$ 194,937	$ 187,383	[1]	$ 362,460	$ 349,705	[1]
Cost of VOIs sold		6,789	1,749	[1]	8,601	4,908	[1]	$ 17,679	$ 28,829
Cost of other fee-based services		16,634	15,374	[1]	34,045	31,481	[1]
Cost reimbursements		14,059	11,893	[1]	30,260	26,563	[1]	52,639	49,557
Selling, general and administrative expenses		109,580	107,488	[1]	203,129	197,323	[1]	421,199	419,929
Interest expense		8,495	8,077	[1]	16,262	15,721	[1]
Total costs and expenses		155,557	144,581	[1]	292,297	275,996	[1]
Income before non-controlling interest and provision for income taxes		$ 39,380	$ 42,802	[1]	70,163	73,709	[1]	136,998	129,624
Add: Depreciation and amortization					$ 7,597	$ 7,012	[1]
Number of reportable segments | segment		2	2		2	2
Corporate And Other [Member]
Segment Reporting Information [Line Items]
Total revenues		$ 2,170	$ 2,411		$ 3,859	$ 4,355
Selling, general and administrative expenses		18,870	14,461		40,462	29,960
Interest expense		3,873	3,533		6,930	6,871
Total costs and expenses		22,743	17,994		47,392	36,831
Income before non-controlling interest and provision for income taxes		(20,573)	(15,583)		(43,533)	(32,476)
Elimination [Member]
Segment Reporting Information [Line Items]
Total revenues		(1,471)	(1,256)		(2,916)	(2,417)
Net carrying cost of VOI inventory		(1,650)	(707)		(4,167)	(2,381)
Cost of other fee-based services		1,650	707		4,167	2,381
Selling, general and administrative expenses		(124)	10		17	340
Mortgage servicing expense		(1,347)	(1,266)		(2,933)	(2,757)
Total costs and expenses		(1,471)	(1,256)		(2,916)	(2,417)
Sales Of VOIs And Financing [Member] | Reportable Segments [Member]
Segment Reporting Information [Line Items]
Total revenues		152,963	150,137		278,705	273,702
Cost of VOIs sold		6,789	1,749		8,601	4,908
Net carrying cost of VOI inventory		1,650	707		4,167	2,381
Cost of other fee-based services		1,115	1,140		2,357	2,426
Selling, general and administrative expenses		90,834	93,017		162,650	167,023
Mortgage servicing expense		1,347	1,266		2,933	2,757
Interest expense		4,622	4,544		9,332	8,850
Total costs and expenses		106,357	102,423		190,040	188,345
Income before non-controlling interest and provision for income taxes		46,606	47,714		88,665	85,357
Add: Depreciation and amortization		1,649	1,497		3,316	3,015
Segment Adjusted EBITDA	[2]	48,255	49,211		91,981	88,372
Resort Operations And Club Management [Member] | Reportable Segments [Member]
Segment Reporting Information [Line Items]
Total revenues		41,275	36,091		82,812	74,065
Cost of other fee-based services		13,869	13,527		27,521	26,674
Cost reimbursements		14,059	11,893		30,260	26,563
Total costs and expenses		27,928	25,420		57,781	53,237
Income before non-controlling interest and provision for income taxes		13,347	10,671		25,031	20,828
Add: Depreciation and amortization		403	397		798	804
Segment Adjusted EBITDA	[2]	13,750	11,068		25,829	21,632
Sales of VOIs [Member]
Segment Reporting Information [Line Items]
Total revenues		68,573	59,405	[1]	124,714	113,641	[1]	242,017	273,874
Sales of VOIs [Member] | Sales Of VOIs And Financing [Member] | Reportable Segments [Member]
Segment Reporting Information [Line Items]
Total revenues		68,573	59,405		124,714	113,641
Fee-Based Sales Commission Revenue [Member]
Segment Reporting Information [Line Items]
Total revenues		60,086	63,915	[1]	105,940	109,069	[1]
Fee-Based Sales Commission Revenue [Member] | Sales Of VOIs And Financing [Member] | Reportable Segments [Member]
Segment Reporting Information [Line Items]
Total revenues		60,086	63,915		105,940	109,069
Other Fee-Based Services Revenue [Member]
Segment Reporting Information [Line Items]
Total revenues		30,391	29,935	[1]	58,415	56,056	[1]
Other Fee-Based Services Revenue [Member] | Sales Of VOIs And Financing [Member] | Reportable Segments [Member]
Segment Reporting Information [Line Items]
Total revenues		3,175	5,737		5,863	8,554
Other Fee-Based Services Revenue [Member] | Resort Operations And Club Management [Member] | Reportable Segments [Member]
Segment Reporting Information [Line Items]
Total revenues		27,216	24,198		52,552	47,502
Cost Reimbursements [Member]
Segment Reporting Information [Line Items]
Total revenues		14,059	11,893	[1]	30,260	26,563	[1]	$ 52,639	$ 49,557
Cost Reimbursements [Member] | Resort Operations And Club Management [Member] | Reportable Segments [Member]
Segment Reporting Information [Line Items]
Total revenues		14,059	11,893		30,260	26,563
Mortgage Servicing Revenue [Member] | Elimination [Member]
Segment Reporting Information [Line Items]
Total revenues		(1,471)	(1,256)		(2,916)	(2,417)
Mortgage Servicing Revenue [Member] | Sales Of VOIs And Financing [Member] | Reportable Segments [Member]
Segment Reporting Information [Line Items]
Total revenues		1,471	1,256		2,916	2,417
Interest Income [Member]
Segment Reporting Information [Line Items]
Total revenues		21,118	21,991	[1]	42,240	44,377	[1]
Interest Income [Member] | Corporate And Other [Member]
Segment Reporting Information [Line Items]
Total revenues		1,460	2,167		2,968	4,356
Interest Income [Member] | Sales Of VOIs And Financing [Member] | Reportable Segments [Member]
Segment Reporting Information [Line Items]
Total revenues		19,658	19,824		39,272	40,021
Other Income (Expense), Net [Member]
Segment Reporting Information [Line Items]
Total revenues		710	244	[1]	891	(1)	[1]
Other Income (Expense), Net [Member] | Corporate And Other [Member]
Segment Reporting Information [Line Items]
Total revenues		$ 710	$ 244		$ 891	$ (1)

[1] * See Note 2 for summary of adjustments.

[2] See Management's Discussion and Analysis of Financial Condition and Results of Operations for information regarding Adjusted EBITDA, including how we define Adjusted EBITDA and a reconciliation of Adjusted EBITDA to net income.