v3.8.0.1
PARTNERS' EQUITY Table 6 - Cash Distributions Paid - General Partner and Common Limited Partners (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 12 Months Ended
Jan. 29, 2018
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
Distribution Made to Limited Partner [Line Items]                        
Cash distributions applicable to common unitbolders and general partner (distribution earned)   $ 115,267 $ 115,084 $ 115,083 $ 117,168         $ 462,602 $ 393,882 $ 392,204
Common Limited Partner [Member]                        
Distribution Made to Limited Partner [Line Items]                        
Cash distributions per unit applicable to limited partners   $ 1.095 $ 1.095 $ 1.095 $ 1.095 $ 1.0950 $ 1.0950 $ 1.0950 $ 1.0950 $ 4.380 $ 4.380 $ 4.380
Distribution date of record (distribution earned)   Feb. 08, 2018 Nov. 09, 2017 Aug. 07, 2017 May 08, 2017              
Distribution payment date   Feb. 13, 2018 Nov. 14, 2017 Aug. 11, 2017 May 12, 2017              
Common Limited Partner [Member] | Subsequent Event [Member]                        
Distribution Made to Limited Partner [Line Items]                        
Distribution announcement date (distribution earned) Jan. 29, 2018