Goodwill and Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended							12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2012 Marcellus	Dec. 31, 2013 Marcellus	Dec. 31, 2013 Northeast Segment	Dec. 31, 2012 Northeast Segment	Dec. 31, 2011 Northeast Segment	Dec. 31, 2013 Southwest Segment	Dec. 31, 2011 Southwest Segment
Changes in goodwill
Gross goodwill beginning of the period	$ 170,879	$ 96,623		$ 74,256	$ 62,445	$ 62,445	$ 62,445	$ 34,178	$ 34,178
Acquisition	2,682	74,256	74,256					2,682
Gross goodwill end of the period	173,561	170,879	74,256	74,256	62,445	62,445	62,445	36,860	34,178
Cumulative impairment	(28,705)							(28,705)
Balance at the end of the period	$ 144,856	$ 142,174		$ 74,256	$ 62,445			$ 8,155