Employees, Retirement and Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Nonvested Restricted Stock Units Activity

A summary of restricted unit activity and changes during the year ended December 31, 2016, is presented below:

Restricted	Units		Weighted- Average Grant-Date Fair Value
Outstanding at January 1, 2016 (nonvested)	101,408		$	33.63
Granted	88,899		32.16
Vesting and transfer of common units to recipients	(61,768	)	32.81
Forfeited	(4,551	)	34.21
Outstanding at December 31, 2016 (nonvested)	123,988		$	32.96

Schedule of Nonvested Performance-based Units Activity

A summary of performance unit activity and changes for the year ended December 31, 2016, is presented below:

Performance Units	Units
Outstanding at January 1, 2016 (nonvested)	45,494
Granted	32,862
Vesting and transfer of common units to recipients	(26,157	)
Forfeited	(2,679	)
Outstanding at December 31, 2016 (nonvested)	49,520