Quarterly Financial Data (Summary of Quarterly Financial Data) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended									12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014		Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Quarterly Financial Data [Abstract]
Revenue	$ 64,853	$ 82,013	$ 95,253	$ 98,001	$ 100,622	$ 66,322		$ 38,460	$ 35,767	$ 340,120		$ 241,171		$ 153,870
Operating income	3,549	10,986	12,631	16,459	15,215	3,528		3,907	5,167
Net income (loss)	$ 544	$ 5,144	$ 6,853	$ 7,591	$ 9,393	$ (5,768)	[1]	$ 3,068	$ 3,526	$ 20,132	[2]	10,219	[2]	$ 22,423	[2]
Basic income per common share	$ 0.02	$ 0.17	$ 0.23	$ 0.25	$ 0.31	$ (0.20)		$ 0.10	$ 0.12
Acquisition deal costs						$ 8,900						$ 8,057

[1] Includes $8.9 million related to Vectren deal costs.

[2] *There is no material difference between net income and comprehensive income.