Organization and Summary of Significant Accounting Policies (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Debt Instrument [Line Items]
Interest costs capitalized	$ 581,000	$ 416,000	$ 1,694,000	$ 1,243,000
Revolving credit facility borrowing capacity	650,000,000		650,000,000
Mortgages
Debt Instrument [Line Items]
Debt costs	147,000		147,000		$ 147,000
Debt costs accumulated amortization	51,000		51,000		38,000
Notes Payable to Banks
Debt Instrument [Line Items]
Debt costs	24,807,000		24,807,000		21,157,000
Debt costs accumulated amortization	$ 7,928,000		$ 7,928,000		$ 6,376,000