Organization and Summary of Significant Accounting Policies (Schedule of Distributions Paid to Shareholders) (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Component Of Operating Cost And Expense [Line Items]
Ordinary income		$ 0.11
Non-dividend distributions	$ 0.84	0.69	$ 0.74
Distribution paid to shareholders	0.84	0.80	0.74
Series A Preferred Shares[Member]
Component Of Operating Cost And Expense [Line Items]
Ordinary income		2.06	1.96
Non-dividend distributions	2.06		0.10
Distribution paid to shareholders	2.06	2.06	2.06
Series B Preferred Shares [Member]
Component Of Operating Cost And Expense [Line Items]
Ordinary income		1.84	1.75
Non-dividend distributions	1.84		0.09
Distribution paid to shareholders	$ 1.84	$ 1.84	$ 1.84