Partners' Capital and Distributions (Distributions) (Details) - USD ($) $ / shares in Units, $ in Thousands |
12 Months Ended | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Nov. 14, 2019 |
Aug. 14, 2019 |
May 15, 2019 |
Feb. 14, 2019 |
Nov. 14, 2018 |
Aug. 14, 2018 |
May 15, 2018 |
Feb. 14, 2018 |
Nov. 14, 2017 |
Aug. 14, 2017 |
May 15, 2017 |
Feb. 14, 2017 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Partners' Capital Notes [Abstract] | |||||||||||||||
| Partners' Capital Account, Distribution Per Unit of Limited Partner Interest (in dollars per share) | $ 1.0200 | $ 1.0125 | $ 1.0050 | $ 0.9975 | $ 0.9775 | $ 0.9575 | $ 0.9375 | $ 0.9200 | $ 0.9050 | $ 0.8900 | $ 0.8725 | $ 0.8550 | $ 4.0350 | $ 3.7925 | $ 3.5225 |
| Limited Partners' Capital Account, Distribution Amount | $ 232,971 | $ 231,258 | $ 229,545 | $ 227,832 | $ 223,061 | $ 218,497 | $ 213,933 | $ 209,940 | $ 206,362 | $ 202,942 | $ 198,951 | $ 194,961 | $ 921,606 | $ 865,431 | $ 803,216 |