CONSOLIDATING FINANCIAL STATEMENTS (Balance Sheets) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
CURRENT ASSETS
Cash and cash equivalents	$ 106,611	$ 112,653
Accounts receivable, less allowance for doubtful accounts	54,340	27,693
Inventory	19,125	24,141
Prepaid expenses	15,774	15,993
Other current assets	2,840	3,047
Total current assets	198,690	183,527
TIMBER AND TIMBERLANDS, NET OF DEPLETION AND AMORTIZATION	2,406,425	2,462,066
HIGHER AND BETTER USE TIMBERLANDS AND REAL ESTATE DEVELOPMENT COSTS	86,955	80,797
NET PROPERTY, PLANT AND EQUIPMENT	22,932	23,378
RESTRICTED CASH	69,638	59,703
INVESTMENT IN SUBSIDIARIES	0	0
INTERCOMPANY RECEIVABLE	0	0
OTHER ASSETS	66,422	49,010
TOTAL ASSETS	2,851,062	2,858,481
CURRENT LIABILITIES
Accounts payable	27,692	25,148
Current maturities of long-term debt	0	3,375
Accrued taxes	5,299	3,781
Accrued payroll and benefits	6,690	9,662
Accrued interest	4,995	5,054
Deferred revenue	17,674	9,721
Other current liabilities	21,538	11,807
Total current liabilities	83,888	68,548
LONG-TERM DEBT, NET OF DEFERRED FINANCING COSTS	972,285	1,022,004
PENSION AND OTHER POSTRETIREMENT BENEFITS	30,230	31,905
OTHER NON-CURRENT LIABILITIES	51,782	43,084
INTERCOMPANY PAYABLE	0	0
TOTAL RAYONIER INC. SHAREHOLDERS’ EQUITY	1,613,489	1,593,023
Noncontrolling interest	99,388	99,917
TOTAL SHAREHOLDERS’ EQUITY	1,712,877	1,692,940	$ 1,496,752
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	2,851,062	2,858,481
Consolidating Adjustments
CURRENT ASSETS
Cash and cash equivalents	0	0
Accounts receivable, less allowance for doubtful accounts	0	0
Inventory	0	0
Prepaid expenses	0	0
Other current assets	0	0
Total current assets	0	0
TIMBER AND TIMBERLANDS, NET OF DEPLETION AND AMORTIZATION	0	0
HIGHER AND BETTER USE TIMBERLANDS AND REAL ESTATE DEVELOPMENT COSTS	0	0
NET PROPERTY, PLANT AND EQUIPMENT	0	0
RESTRICTED CASH	0	0
INVESTMENT IN SUBSIDIARIES	(4,274,507)	(4,345,564)
INTERCOMPANY RECEIVABLE	0	0
OTHER ASSETS	0	0
TOTAL ASSETS	(4,274,507)	(4,345,564)
CURRENT LIABILITIES
Accounts payable	0	0
Current maturities of long-term debt		0
Accrued taxes	0	0
Accrued payroll and benefits	0	0
Accrued interest	0	0
Deferred revenue	0	0
Other current liabilities	0	0
Total current liabilities	0	0
LONG-TERM DEBT, NET OF DEFERRED FINANCING COSTS	0	0
PENSION AND OTHER POSTRETIREMENT BENEFITS	0	0
OTHER NON-CURRENT LIABILITIES	0	0
INTERCOMPANY PAYABLE	0	0
TOTAL RAYONIER INC. SHAREHOLDERS’ EQUITY	(4,274,507)	(4,345,564)
Noncontrolling interest	0	0
TOTAL SHAREHOLDERS’ EQUITY	(4,274,507)	(4,345,564)
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	(4,274,507)	(4,345,564)
Rayonier Inc. (Parent Issuer) | Reportable Legal Entities
CURRENT ASSETS
Cash and cash equivalents	76,980	48,564
Accounts receivable, less allowance for doubtful accounts	1,995	0
Inventory	0	0
Prepaid expenses	0	0
Other current assets	0	0
Total current assets	78,975	48,564
TIMBER AND TIMBERLANDS, NET OF DEPLETION AND AMORTIZATION	0	0
HIGHER AND BETTER USE TIMBERLANDS AND REAL ESTATE DEVELOPMENT COSTS	0	0
NET PROPERTY, PLANT AND EQUIPMENT	0	0
RESTRICTED CASH	0	0
INVESTMENT IN SUBSIDIARIES	1,516,631	1,531,156
INTERCOMPANY RECEIVABLE	37,826	40,067
OTHER ASSETS	3	2
TOTAL ASSETS	1,633,435	1,619,789
CURRENT LIABILITIES
Accounts payable	0	0
Current maturities of long-term debt		0
Accrued taxes	0	0
Accrued payroll and benefits	0	0
Accrued interest	3,047	3,047
Deferred revenue	0	0
Other current liabilities	1,995	0
Total current liabilities	5,042	3,047
LONG-TERM DEBT, NET OF DEFERRED FINANCING COSTS	323,618	323,434
PENSION AND OTHER POSTRETIREMENT BENEFITS	0	0
OTHER NON-CURRENT LIABILITIES	0	0
INTERCOMPANY PAYABLE	(308,714)	(299,715)
TOTAL RAYONIER INC. SHAREHOLDERS’ EQUITY	1,613,489	1,593,023
Noncontrolling interest	0	0
TOTAL SHAREHOLDERS’ EQUITY	1,613,489	1,593,023
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	1,633,435	1,619,789
Subsidiary Guarantors | Reportable Legal Entities
CURRENT ASSETS
Cash and cash equivalents	11,964	25,042
Accounts receivable, less allowance for doubtful accounts	1,814	3,726
Inventory	0	0
Prepaid expenses	1,924	759
Other current assets	106	14
Total current assets	15,808	29,541
TIMBER AND TIMBERLANDS, NET OF DEPLETION AND AMORTIZATION	0	0
HIGHER AND BETTER USE TIMBERLANDS AND REAL ESTATE DEVELOPMENT COSTS	0	0
NET PROPERTY, PLANT AND EQUIPMENT	17,459	21
RESTRICTED CASH	0	0
INVESTMENT IN SUBSIDIARIES	2,757,876	2,814,408
INTERCOMPANY RECEIVABLE	(628,749)	(628,167)
OTHER ASSETS	32,274	12,680
TOTAL ASSETS	2,194,668	2,228,483
CURRENT LIABILITIES
Accounts payable	3,980	2,838
Current maturities of long-term debt		0
Accrued taxes	8	48
Accrued payroll and benefits	3,864	5,298
Accrued interest	1,948	1,995
Deferred revenue	0	0
Other current liabilities	593	564
Total current liabilities	10,393	10,743
LONG-TERM DEBT, NET OF DEFERRED FINANCING COSTS	648,667	663,570
PENSION AND OTHER POSTRETIREMENT BENEFITS	30,914	32,589
OTHER NON-CURRENT LIABILITIES	7,025	9,386
INTERCOMPANY PAYABLE	(18,962)	(18,961)
TOTAL RAYONIER INC. SHAREHOLDERS’ EQUITY	1,516,631	1,531,156
Noncontrolling interest	0	0
TOTAL SHAREHOLDERS’ EQUITY	1,516,631	1,531,156
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	2,194,668	2,228,483
Non- guarantors | Reportable Legal Entities
CURRENT ASSETS
Cash and cash equivalents	17,667	39,047
Accounts receivable, less allowance for doubtful accounts	50,531	23,967
Inventory	19,125	24,141
Prepaid expenses	13,850	15,234
Other current assets	2,734	3,033
Total current assets	103,907	105,422
TIMBER AND TIMBERLANDS, NET OF DEPLETION AND AMORTIZATION	2,406,425	2,462,066
HIGHER AND BETTER USE TIMBERLANDS AND REAL ESTATE DEVELOPMENT COSTS	86,955	80,797
NET PROPERTY, PLANT AND EQUIPMENT	5,473	23,357
RESTRICTED CASH	69,638	59,703
INVESTMENT IN SUBSIDIARIES	0	0
INTERCOMPANY RECEIVABLE	590,923	588,100
OTHER ASSETS	34,145	36,328
TOTAL ASSETS	3,297,466	3,355,773
CURRENT LIABILITIES
Accounts payable	23,712	22,310
Current maturities of long-term debt		3,375
Accrued taxes	5,291	3,733
Accrued payroll and benefits	2,826	4,364
Accrued interest	0	12
Deferred revenue	17,674	9,721
Other current liabilities	18,950	11,243
Total current liabilities	68,453	54,758
LONG-TERM DEBT, NET OF DEFERRED FINANCING COSTS	0	35,000
PENSION AND OTHER POSTRETIREMENT BENEFITS	(684)	(684)
OTHER NON-CURRENT LIABILITIES	44,757	33,698
INTERCOMPANY PAYABLE	327,676	318,676
TOTAL RAYONIER INC. SHAREHOLDERS’ EQUITY	2,757,876	2,814,408
Noncontrolling interest	99,388	99,917
TOTAL SHAREHOLDERS’ EQUITY	2,857,264	2,914,325
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$ 3,297,466	$ 3,355,773