Interest Rate Swap Agreements - Sensitivity Analysis (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Agreement effective date April 13, 2015 | Increase of 50 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	$ 28
Agreement effective date April 13, 2015 | Decrease of 50 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	28
Agreement effective date April 13, 2015 | Increase of 100 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	28
Agreement effective date April 13, 2015 | Decrease of 100 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	28
Agreement effective date October 1, 2015 | Increase of 50 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	1,532
Agreement effective date October 1, 2015 | Decrease of 50 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	(88)
Agreement effective date October 1, 2015 | Increase of 100 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	2,318
Agreement effective date October 1, 2015 | Decrease of 100 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	(924)
Agreement entered into March 23, 2016 effective date December 24, 2018 | Increase of 50 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	1,317
Agreement entered into March 23, 2016 effective date December 24, 2018 | Decrease of 50 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	49
Agreement entered into March 23, 2016 effective date December 24, 2018 | Increase of 100 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	1,936
Agreement entered into March 23, 2016 effective date December 24, 2018 | Decrease of 100 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	(601)
Agreement entered into March 31, 2016 effective date December 24, 2018 | Increase of 50 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	583
Agreement entered into March 31, 2016 effective date December 24, 2018 | Decrease of 50 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	77
Agreement entered into March 31, 2016 effective date December 24, 2018 | Increase of 100 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	830
Agreement entered into March 31, 2016 effective date December 24, 2018 | Decrease of 100 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	(183)
Agreement entered into March 31, 2016 effective date April 13, 2019 | Increase of 50 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	739
Agreement entered into March 31, 2016 effective date April 13, 2019 | Decrease of 50 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	26
Agreement entered into March 31, 2016 effective date April 13, 2019 | Increase of 100 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	1,086
Agreement entered into March 31, 2016 effective date April 13, 2019 | Decrease of 100 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	(339)
Agreement entered into June 12, 2017 effective date March 02, 2018 | Increase of 50 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	1,479
Agreement entered into June 12, 2017 effective date March 02, 2018 | Decrease of 50 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	(1,012)
Agreement entered into June 12, 2017 effective date March 02, 2018 | Increase of 100 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	2,671
Agreement entered into June 12, 2017 effective date March 02, 2018 | Decrease of 100 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	(2,314)
Agreement entered into November 15, 2018 effective date November 30, 2020 | Increase of 50 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	92
Agreement entered into November 15, 2018 effective date November 30, 2020 | Decrease of 50 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	(2,374)
Agreement entered into November 15, 2018 effective date November 30, 2020 | Increase of 100 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	1,245
Agreement entered into November 15, 2018 effective date November 30, 2020 | Decrease of 100 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, increase (decrease) in fair value of interest rate derivative	$ (3,691)
Interest Rate Swap Agreement | Increase of 50 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, assumed increase (decrease) in basis points (as a percent)	0.50%
Interest Rate Swap Agreement | Decrease of 50 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, assumed increase (decrease) in basis points (as a percent)	(0.50%)
Interest Rate Swap Agreement | Increase of 100 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, assumed increase (decrease) in basis points (as a percent)	1.00%
Interest Rate Swap Agreement | Decrease of 100 Basis Points
Interest Rate Swap Agreements
Sensitivity analysis, assumed increase (decrease) in basis points (as a percent)	(1.00%)