Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2016

Summary of Property, Plant and Equipment by Classification

A summary of property, plant and equipment by classification as of December 31, 2016 and 2015 is provided in the following table:



	As of December 31,
(in thousands)	2016			2015
Property, plant and equipment
Regulated Energy
Natural gas distribution – Delmarva	$	220,083		$	207,127
Natural gas distribution – Florida	331,281			286,538
Natural gas transmission – Delmarva	285,746			249,274
Natural gas transmission – Florida	27,018			20,291
Electric distribution – Florida	93,553			79,526
Unregulated Energy
Propane distribution – Delmarva	73,686			66,403
Propane distribution – Florida	26,359			24,589
Other Unregulated natural gas services – Ohio	61,383			54,607
CHP - Florida	35,237			—
Other unregulated energy	135			135
Other	21,114			18,999
Total property, plant and equipment	1,175,595			1,007,489
Less: Accumulated depreciation and amortization	(245,207		)	(215,313		)
Plus: Construction work in progress	56,276			62,774
Net property, plant and equipment	$	986,664		$	854,950

Average Depreciation Rates

We compute depreciation expense for our regulated operations by applying composite, annual rates, as approved by the respective regulatory bodies. The following table shows the average depreciation rates used for regulated operations during the years ended December 31, 2016, 2015 and 2014:



	2016	2015	2014
Natural gas distribution – Delmarva	2.5%	2.4%	2.5%
Natural gas distribution – Florida	2.9%	2.9%	2.9%
Natural gas transmission – Delmarva	2.7%	2.7%	2.7%
Natural gas transmission – Florida	3.9%	4.0%	4.0%
Electric distribution – Florida	3.5%	3.5%	3.8%

Estimated Useful Lives of Assets

For our unregulated operations, we compute depreciation expense on a straight line basis over the following estimated useful lives of the assets:



Asset Description	Useful Life
Propane distribution mains	10-37 years
Propane bulk plants and tanks	10-40 years
Propane equipment	5-33 years
Meters and meter installations	5-33 years
Measuring and regulating station equipment	5-37 years
Natural gas pipelines	45 years
Natural gas right of ways	Perpetual
CHP plant	30 years
Natural gas processing equipment	20-25 years
Office furniture and equipment	3-10 years
Transportation equipment	4-20 years
Structures and improvements	5-45 years
Other	Various