SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Detail)	12 Months Ended
	Dec. 31, 2019 USD ($) segment shares	Dec. 31, 2018 USD ($) $ / shares	Dec. 31, 2017 USD ($)	Dec. 31, 2019	Dec. 31, 2019 property	Dec. 31, 2019 $ / shares	Dec. 31, 2019 facility	Jan. 01, 2019 USD ($)	Jan. 01, 2018 USD ($)
Accounting Policies [Line Items]
Impairment on real estate properties	$ 45,264,000	$ 29,839,000	$ 99,070,000
Loan loss reserves	5,100,000	108,100,000
Equity method investment, other than temporary impairment	0	0	0
Cash, FDIC insured amount	250,000
Lease inducements	92,628,000	49,644,000
Accrued expenses and other liabilities	312,040,000	272,172,000
Provisions for uncollectible accounts		6,689,000	14,580,000
Recovery of provisions for other losses		4,800,000
Impairment of goodwill	$ 0	0	0
Number of Operating Segments | segment	1
Provision of of straight-line rent and contractual receivables	$ 11,100,000	11,500,000
Annual percentage increases over the rents of the prior year, minimum				2.00%
Annual percentage increases over the rents of the prior year, maximum				3.00%
Amortization of financing cost	$ 9,564,000	$ 8,960,000	9,516,000
Common stock, par value (in dollars per share) | $ / shares		$ 0.10				$ 0.10
Number of units tendered for redemption of unregistered shares | shares	1
Number of facilities owned | facility							987
Purchase price of buildings acquired paid in cash	$ 1,325,400,000	$ 105,700,000	412,700,000
Net cash provided by (used in) operating activities	553,747,000	499,373,000	577,912,000
Increase in cash, cash equivalents, and restricted cash	21,709,000	(85,137,000)	(10,468,000)
Operating lease, right of use asset	17,533,000
Lease liability	18,033,000
Cumulative effect of accounting change	(8,490,000)		10,000,000
Rental income	804,076,000	767,340,000	775,176,000
Real estate tax expense	14,933,000
General and administrative - ground lease expense	$ 1,208,000
Depreciation method	straight-line basis
Incentive To Lessee	$ 92,628,000	49,644,000
Contractual Receivable [Member]
Accounting Policies [Line Items]
Provision of of straight-line rent and contractual receivables			9,300,000
Straight-Line Rent Receivable [Member]
Accounting Policies [Line Items]
Provisions for uncollectible accounts			4,100,000
Accounting Standards Update 2014-09 [Member]
Accounting Policies [Line Items]
Deferred gain resulting from sale of facilities to third party through retained earnings									$ 10,000,000.0
Accounting Standards Update 2016-02 [Member]
Accounting Policies [Line Items]
Operating lease, right of use asset								$ 11,100,000
Cumulative effect of accounting change								$ 8,500,000
Rental income	12,100,000
Real estate tax expense	14,900,000
Cash Flow Hedging [Member]
Accounting Policies [Line Items]
Cash flow hedges recorded at fair value	$ 3,700,000	4,000,000.0
Omega OP
Accounting Policies [Line Items]
Percentage of limited partnership interests owned	97.00%
Omega Op Units [Member] | Omega OP
Accounting Policies [Line Items]
Percentage of limited partnership interests owned	97.00%
Other Investors | Omega OP
Accounting Policies [Line Items]
Percentage of limited partnership interests owned	3.00%
Genesis HealthCare
Accounting Policies [Line Items]
Lease inducements	$ 15,000,000.0
Incentive To Lessee	15,000,000.0
Existing Operator
Accounting Policies [Line Items]
Payment made to operator to buyout out in money purchase option		50,000,000
Lease inducements		28,000,000
Provision of of straight-line rent and contractual receivables	1,200,000
Incentive To Lessee		28,000,000
Reduction of contingent liability amount		22,000,000
Existing Operator | Accounting Standards Update 2016-02 [Member]
Accounting Policies [Line Items]
Rental income	800,000
General and administrative - ground lease expense	1,200,000
Seven Other Existing Operators [Member]
Accounting Policies [Line Items]
Lease inducements	35,800,000
Incentive To Lessee	35,800,000
Five Operators [Member]
Accounting Policies [Line Items]
Provision of of straight-line rent and contractual receivables	9,900,000
Certain Operators [Member]
Accounting Policies [Line Items]
Lease inducements	50,800,000
Incentive To Lessee	$ 50,800,000
Building | Minimum
Accounting Policies [Line Items]
Estimated useful lives	20 years
Building | Maximum
Accounting Policies [Line Items]
Estimated useful lives	40 years
Site improvements | Minimum
Accounting Policies [Line Items]
Estimated useful lives	8 years
Site improvements | Maximum
Accounting Policies [Line Items]
Estimated useful lives	15 years
Furniture and Equipment
Accounting Policies [Line Items]
Purchase price of buildings acquired paid in cash	$ 78,900,000	$ 5,900,000	$ 24,500,000
Furniture and Equipment | Minimum
Accounting Policies [Line Items]
Estimated useful lives	3 years
Furniture and Equipment | Maximum
Accounting Policies [Line Items]
Estimated useful lives	10 years
Skill Nursing Facilities Leases [Member]
Accounting Policies [Line Items]
Number of facilities owned					782		784
Assisted Living Facilities Leased [Member]
Accounting Policies [Line Items]
Number of facilities owned					114		114
Specialty Facilities Leased [Member]
Accounting Policies [Line Items]
Number of facilities owned					28		28
Medical Office Buildings Leased [Member]
Accounting Policies [Line Items]
Number of facilities owned | facility							2