Fair Value of Financial Instruments - Financial Instruments Measured at Fair Value (Details) - Fair Value Measurements Recurring $ in Thousands	Dec. 31, 2018 USD ($)
Level 1
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Total financial assets	$ 0
Level 1 | Interest rate swaps
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Total financial assets	0
Level 1 | Interest rate cap
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Total financial assets	0
Level 2
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Total financial assets	2,434
Level 2 | Interest rate swaps
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Total financial assets	2,429
Level 2 | Interest rate cap
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Total financial assets	5
Carrying and Fair Value
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Total financial assets	2,434
Carrying and Fair Value | Interest rate swaps
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Total financial assets	2,429
Carrying and Fair Value | Interest rate cap
Financial Instruments Measured at Fair Value: Available-for-sale securities - (Corporate equity securities)
Total financial assets	$ 5