Related-Party Transactions, Summary of Transactions (Details) (USD $)	3 Months Ended				6 Months Ended		3 Months Ended				6 Months Ended				0 Months Ended
	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Tesoro		Jun. 30, 2013 Tesoro		Jun. 30, 2014 Tesoro		Jun. 30, 2013 Tesoro		Jul. 24, 2014 Subsequent Event
Related Party Transactions
Revenues	$ 114,214,000			$ 54,102,000	$ 223,794,000	$ 101,994,000	$ 114,214,000		$ 54,102,000		$ 223,794,000		$ 101,994,000
Operating and maintenance expenses							8,309,000	[1]	9,741,000	[1]	18,580,000	[1]	13,179,000	[1]
General and administrative expenses							9,228,000		4,047,000		16,708,000		6,873,000
Imbalance settlement gains	2,700,000			2,576,000	5,117,000	5,000,000
Quarterly distributions
Cash distributions paid to Tesoro and TLGP					$ 34,400,000										$ 20,300,000
Declaration date															Jul. 24, 2014
Cash distributions per unit (dollars per unit)		$ 0.590	$ 0.565												$ 0.615	[2]
Distribution date		May 15, 2014	Feb. 13, 2014												Aug. 14, 2014	[2]

[1] Operating and maintenance expenses include imbalance settlement gains of $2.7 million and $2.6 million for the three months ended June 30, 2014 and 2013, respectively, and $5.1 million and $5.0 million for the six months ended June 30, 2014 and 2013, respectively.

[2] This distribution was declared on July 24, 2014 and will be paid on the date of distribution.