Equity, Units Rollforward (Details) (USD $)	3 Months Ended		6 Months Ended				6 Months Ended					6 Months Ended				1 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014		Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014 Tesoro	Jun. 30, 2014 Common		Jun. 30, 2014 Public common units	Jun. 30, 2014 Tesoro common units	Jun. 30, 2014 Subordinated		Jun. 30, 2014 General Partner		Jul. 31, 2014 Subsequent Event
Common units outstanding (units)	54,461,052		54,461,052			39,148,916				35,350,338	19,110,714
General partner units outstanding (units)	1,110,282		1,110,282			1,110,282								1,110,282
General partner's ownership interest	2.00%	2.00%	2.00%		2.00%
Tesoro's ownership interest							36.00%
Subordinated units effective conversion Date			May 16, 2014
Subordinated units converted into common units			0					15,254,890				(15,254,890)		0
ATM Program, filing date			Jun. 25, 2014
Common units, aggregate value, ATM Program	$ 200,000,000		$ 200,000,000
Issuance of common units under ATM Program			5,500					5,500				0		0		193,900
Equity offering, net of issuance costs, ATM Program			387,000					379,000				0		8,000		13,600,000
Fees for issuance of units under ATM Program	$ 7,903		$ 7,903													$ 286,501
Changes in Units Outstanding
Balance at December 31, 2013			55,514,088					39,148,916				15,254,890		1,110,282
Issuance of units under ATM Program			5,500					5,500				0		0		193,900
Unit-based compensation awards			51,746	[1]				51,746	[1]			0	[1]	0	[1]
Subordinated unit conversion			0					15,254,890				(15,254,890)		0
Balance at June 30, 2014	55,571,334		55,571,334					54,461,052				0		1,110,282
Equity-based compensation units withheld for taxes (units)								22,933

[1] (a) Unit-based compensation awards are presented net of 22,933 units withheld for taxes.