- Financial Instruments Measured at Fair Value (Details)	Dec. 31, 2017 USD ($)
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Derivative liabilities	$ 2,200
Fair Value Measurements Recurring | Level 1
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Derivative assets	0
Fair Value Measurements Recurring | Level 1 | Interest rate swaps
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Derivative liabilities	0
Fair Value Measurements Recurring | Level 2
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Derivative assets	1,951,000
Fair Value Measurements Recurring | Level 2 | Interest rate swaps
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Derivative assets	1,948,000
Derivative liabilities	1,000
Fair Value Measurements Recurring | Level 2 | Interest rate cap
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Derivative assets	3,000
Fair Value Measurements Recurring | Carrying and Fair Value
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Derivative assets	1,951,000
Fair Value Measurements Recurring | Carrying and Fair Value | Interest rate swaps
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Derivative assets	1,948,000
Derivative liabilities	1,000
Fair Value Measurements Recurring | Carrying and Fair Value | Interest rate cap
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Derivative assets	$ 3,000