Segment Information (Details 5) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Assets
Certain cash and cash equivalents	$ 85,305	$ 345,756	$ 114,332	$ 64,537
Fair value of derivatives	11,962	30,382
Investment in unconsolidated affiliates	75,627	63,054
Total assets	9,396,423	6,728,362
Total segments
Segment Assets
Total assets	9,137,935	6,276,468
Unallocated Segment
Segment Assets
Certain cash and cash equivalents	63,086	261,473
Fair value of derivatives	11,962	30,382
Investment in unconsolidated affiliates	75,627	63,054
Other	107,813	96,985
Marcellus | Total segments
Segment Assets
Total assets	4,529,028	3,172,144
Utica Segment | Total segments
Segment Assets
Total assets	1,646,995	439,987
Northeast Segment | Total segments
Segment Assets
Total assets	572,855	578,122
Southwest Segment | Total segments
Segment Assets
Total assets	$ 2,389,057	$ 2,086,215