Investments in Non-Consolidated Subsidiaries Investments in Non-Consolidated Subsidiaries (Investment Summary) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended											12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 White Cliffs Pipeline, LLC [Member]	Dec. 31, 2012 White Cliffs Pipeline, LLC [Member]	Dec. 31, 2011 White Cliffs Pipeline, LLC [Member]	Dec. 31, 2013 Ngl Energy Partners Lp [Member]		Dec. 31, 2012 Ngl Energy Partners Lp [Member]	Dec. 31, 2011 Ngl Energy Partners Lp [Member]	Nov. 01, 2011 Ngl Energy Partners Lp [Member]	Dec. 31, 2013 Glass Mountain Pipeline Llc [Member]	Dec. 31, 2012 Glass Mountain Pipeline Llc [Member]	Dec. 31, 2011 Glass Mountain Pipeline Llc [Member]	Dec. 31, 2013 Return of and return on capital [Member]	Dec. 31, 2012 Return of and return on capital [Member]	Dec. 31, 2011 Return of and return on capital [Member]
Schedule of Equity Method Investments [Line Items]
Distributions from equity investments									$ 63,651	$ 36,440	$ 15,004	$ 57,576	$ 44,514	$ 27,459	$ 18,321		$ 9,217	$ 0		$ 0	$ 0	$ 0	$ 75,897	$ 53,731	$ 27,459
Earnings from equity method investments	12,788	7,483	14,861	17,345	13,133	3,116	12,289	7,498	52,477	36,036	15,004	45,459	36,439	15,004	7,123	[1]	(403)	0		(105)	0	0
Equity method investments	$ 565,124				$ 387,802				$ 565,124	$ 387,802		$ 224,095	$ 138,970		$ 208,848		$ 174,398		$ 184,000	$ 132,181	$ 74,434

[1] * Excluding gain on issuance of common units of $26.9 million.