Related Party Transactions - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Related Party Transaction [Line Items]
Allocations of expenses for general and administrative services	$ 0	$ 0
Rental income from related party	0	14,000,000	$ 16,308,000	$ 18,667,000
Tenant reimbursements from related party	0	1,228,000	1,406,000	1,624,000
Account receivable due from related party for tenant reimbursement	0		0		$ 2,275,000
Net contribution from (distribution to) Ensign			0	4,356,000
Allocation Of Corporate Expenses [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Allocations of expenses for general and administrative services			0	7,400,000
Rental Income From Affiliate [Member] | Director [Member]
Related Party Transaction [Line Items]
Rental income from related party	0	14,000,000	16,300,000	18,700,000
Tenant reimbursements from related party	$ 0	$ 1,200,000	$ 1,400,000	1,600,000
Account receivable due from related party for tenant reimbursement					$ 2,300,000
Centralized Cash Management System [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Net contribution from (distribution to) Ensign				$ 4,400,000