Net Income Per Limited Partner Unit - Reconciliation of Net Income (Loss) and Weighted-Average Units Used in Computing Basic and Diluted Net Income (Loss) Per Limited Partner Unit (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Numerator:
Distributions paid										$ 88,226	$ 83,558	$ 66,094
Denominator:
Weighted average limited partnership units outstanding-basic										33,844,823	32,159,156	21,462,665
Weighted average limited partnership units outstanding - diluted										33,855,345	32,216,004	21,561,403
Net income per limited partnership unit - basic		$ 0.59	$ 0.10	$ (0.15)	$ 0.02	$ 0.04	$ 0.06	$ 0.08	$ 0.03	$ 0.56	$ 0.22	$ 0.35
Net income per limited partnership unit - diluted		$ 0.59	$ 0.10	$ (0.15)	$ 0.02	$ 0.04	$ 0.06	$ 0.08	$ 0.03	$ 0.56	$ 0.22	$ 0.35
Common Units
Numerator:
Distributions paid	[1]									$ 83,786	$ 75,598	$ 47,798
Allocation of distributions in excess of net income	[2]									(64,965)	(68,539)	(40,356)
Limited partners’ interest in net income - basic										18,821	7,059	7,442
Adjustment for phantom units												9
Limited partners’ interest in net income - diluted										$ 18,821	$ 7,059	$ 7,451
Denominator:
Weighted average limited partnership units outstanding-basic										33,844,823	32,159,156	21,462,665
Adjustment for phantom units										10,522	56,848	98,738
Weighted average limited partnership units outstanding - diluted										33,855,345	32,216,004	21,561,403
Net income per limited partnership unit - basic										$ 0.56	$ 0.22	$ 0.35
Net income per limited partnership unit - diluted										$ 0.56	$ 0.22	$ 0.35
Subordinated Units
Numerator:
Distributions paid	[1]										$ 4,459	$ 16,781
Allocation of distributions in excess of net income	[2]										(4,206)	(14,172)
Limited partners’ interest in net income - basic											253	2,609
Adjustment for phantom units											0
Limited partners’ interest in net income - diluted											$ 253	$ 2,609
Denominator:
Weighted average limited partnership units outstanding-basic											1,151,366	7,525,000
Adjustment for phantom units											0	0
Weighted average limited partnership units outstanding - diluted											1,151,366	7,525,000
Net income per limited partnership unit - basic											$ 0.22	$ 0.35
Net income per limited partnership unit - diluted											$ 0.22	$ 0.35

[1] Distributions paid per unit were $2.48, $2.40 and $2.23 during 2017, 2016 and 2015, respectively.

[2] Allocation of distributions in excess of net income is based on a pro rata proportion to the common and subordinated units as outlined in the Partnership Agreement.