Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ 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
Condensed Financial Statements, Captions [Line Items]
Total revenues	$ 575,897	$ 680,670	$ 735,904	$ 607,396	$ 751,222	$ 915,719	$ 970,337	$ 864,610	$ 2,599,867	$ 3,501,888	$ 3,407,128
Total operating costs and expenses	554,141	654,305	714,873	589,835	728,848	899,864	953,914	848,967	2,513,154	3,431,593	3,449,588
Operating Income (Loss)	21,756	26,365	21,031	17,561	22,374	15,855	16,423	15,643	86,713	70,295	(42,460)
Net income (loss)	15,387	20,174	14,653	13,411	20,988	15,390	16,012	15,206	63,625	67,596	(42,727)
Earnings Per Share [Abstract]
Net income attributable to limited partners	$ 14,842	$ 16,493	$ 15,915	$ 15,323	$ 18,819	$ 12,265	$ 10,975	$ 10,933	$ 62,573	$ 52,992	$ 8,528
Earnings Per Share, Basic	$ 0.30	$ 0.35	$ 0.34	$ 0.33	$ 0.40	$ 0.27	$ 0.24	$ 0.24
Earnings Per Share, Diluted	0.30	0.35	0.34	0.33	0.40	0.27	0.24	0.24
Earnings Per Share, Basic and Diluted	$ 0.29	$ 0.35	$ 0.34	$ 0.33	$ 0.40	$ 0.27	$ 0.24	$ 0.24
Weighted Average Number of Shares Outstanding, Basic	24,314	24,017	24,017	23,985	23,795	22,811	22,811	22,811
Weighted Average Number of Shares Outstanding, Diluted	24,321	24,024	24,051	23,996	23,861	22,883	22,861	22,815
Weighted Average Number of Shares Outstanding, Basic and Diluted	22,811	22,811	22,811	22,811	22,811	22,811	22,811	22,811
Scenario, Previously Reported [Member]
Condensed Financial Statements, Captions [Line Items]
Total revenues		$ 674,479	$ 734,501	$ 607,396	$ 751,222	$ 915,719	$ 970,337	$ 864,610
Total operating costs and expenses		651,795	712,208	587,923	727,674	899,000	952,863	847,849
Operating Income (Loss)		22,684	22,293	19,473	23,548	16,719	17,474	16,761
Net income (loss)		16,493	15,915	15,323	22,159	16,250	17,060	16,324
Scenario, Adjustment [Member]
Condensed Financial Statements, Captions [Line Items]
Total revenues		6,191	1,403	0	0	0	0	0
Total operating costs and expenses		2,510	2,665	1,912	1,174	864	1,051	1,118
Operating Income (Loss)		3,681	(1,262)	(1,912)	(1,174)	(864)	(1,051)	(1,118)
Net income (loss)		$ 3,681	$ (1,262)	$ (1,912)	$ (1,171)	$ (860)	$ (1,048)	$ (1,118)