Unit Option Activity (Details) - Options $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options outstanding at beginning of period (in shares) | shares	368
Exercised (in shares) | shares	(7)
Options outstanding at end of period (in shares) | shares	362
Options exercisable (in shares) | shares	362
Weighted Average Exercise Price
Options outstanding at beginning of period (in dollars per share) | $ / shares	$ 34.51
Exercised (in dollars per share) | $ / shares	35.97
Options outstanding at end of period (in dollars per share) | $ / shares	34.49
Options exercisable (in dollars per share) | $ / shares	$ 34.49
Weighted Average Remaining Contractual Life	2 years 9 months 18 days
Aggregate Intrinsic Value | $	$ 7,575