Derivative Instruments - Outstanding Derivative Instruments (Details) - Interest Rate Swap - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Derivative [Line Items]
Aggregate Notional Amount	$ 405,293	$ 428,652
AP4
Derivative [Line Items]
Fixed Interest Rate	2.338%	2.338%
Aggregate Notional Amount	$ 100,551	$ 102,921
AP6WII
Derivative [Line Items]
Fixed Interest Rate	0.00%
Aggregate Notional Amount	$ 0	$ 72,025
AP6WII | Minimum
Derivative [Line Items]
Fixed Interest Rate		2.402%
AP6WII | Maximum
Derivative [Line Items]
Fixed Interest Rate		3.254%
LAPH
Derivative [Line Items]
Fixed Interest Rate	3.409%	3.409%
Aggregate Notional Amount	$ 43,512	$ 44,205
EZOP
Derivative [Line Items]
Aggregate Notional Amount	$ 47,542	$ 55,290
EZOP | Minimum
Derivative [Line Items]
Fixed Interest Rate	2.015%	1.90%
EZOP | Maximum
Derivative [Line Items]
Fixed Interest Rate	2.62%	3.014%
TEPIH
Derivative [Line Items]
Fixed Interest Rate	0.00%
Aggregate Notional Amount	$ 0	$ 99,536
TEPIH | Minimum
Derivative [Line Items]
Fixed Interest Rate		2.35%
TEPIH | Maximum
Derivative [Line Items]
Fixed Interest Rate		3.104%
TEPIIH
Derivative [Line Items]
Aggregate Notional Amount	$ 197,463	$ 54,675
TEPIIH | Minimum
Derivative [Line Items]
Fixed Interest Rate	2.31%	2.995%
TEPIIH | Maximum
Derivative [Line Items]
Fixed Interest Rate	3.383%	3.383%
TEPH
Derivative [Line Items]
Fixed Interest Rate	1.62%	0.00%
Aggregate Notional Amount	$ 16,225	$ 0