Long-Term Debt and Capital Leases (Details) (USD $)	1 Months Ended		12 Months Ended							0 Months Ended										12 Months Ended		12 Months Ended
	Aug. 31, 2011	Mar. 31, 2010	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2012 Redemption of Notes [Member]	Mar. 26, 2010 Senior Notes [Member]	Dec. 31, 2012 Senior Notes [Member]		Dec. 31, 2011 Senior Notes [Member]		Dec. 31, 2012 Revolving Loan Facility [Member]		Dec. 31, 2011 Revolving Loan Facility [Member]		Nov. 10, 2005 Revolving Loan Facility [Member]	Dec. 31, 2012 Revolving Loan Facility [Member] Minimum [Member]	Dec. 05, 2011 Revolving Loan Facility [Member] Minimum [Member]	Dec. 31, 2012 Revolving Loan Facility [Member] Maximum [Member]	Dec. 05, 2011 Revolving Loan Facility [Member] Maximum [Member]	Dec. 31, 2012 Twelve Month Period Beginning April 1, 2014 [Member] Redemption of Notes [Member]	Dec. 31, 2012 Twelve Month Period Beginning April 1, 2015 [Member] Redemption of Notes [Member]	Dec. 31, 2012 Twelve Month Period Beginning April 1, 2016 [Member] Redemption of Notes [Member]	Dec. 31, 2011 Letter of Credit [Member] Revolving Loan Facility [Member]
Debt Instrument [Line Items]
Face amount											$ 200,000,000				$ 400,000,000
Stated interest rate											8.875%
Proceeds from issuance from senior notes			727,000,000	[1]	529,000,000	[1]	503,856,000	[1]		197,200,000
Partnership redemption option maximum									35.00%
Partnership senior note redemption option price									108.875%															104.438%	102.219%	100.00%
Default period			30 days
Period after notice to comply with reporting obligation under the Securities Exchange Act of 1934			180 days
Period of notice to comply with any of the other agreements in this Indenture			60 days
Default aggregate principal amount of indebtedness plus any other principal amount that has been accelerated			20,000,000
Final judgement payment period			60 days
Notice to issuers or holders of principal amount outstanding, minimum			25.00%
Maximum amount of borrowings and letters of credit available under Credit Facility																			225,000,000		375,000,000		400,000,000
Amount outstanding			478,198,000		460,202,000						173,388,000	[2],[3]	197,808,000	[2],[3]	296,000,000	[4],[5]	250,000,000	[4],[5]
Letters of cedit outstanding																											120,000
Amount available under revolving credit facility																	103,880,000
Line of credit draws during the year																				35,000,000		361,000,000
Maximum permitted leverage ratio															5.00
Maximum senior leverage ratio															3.25
Minimum consolidated interest coverage ratio															2.75
Percent of commitments provided by lenders															50.00%
Amount if received from indebtedness partnership must prepay															15,000,000
Derivative termination fes		3,850,000
Notional value of derivatives canceled	100,000,000
Early extinguishment termination fees received	2,800,000
Cash paid for interest			29,239,000		22,818,000		23,663,000
Capitalized interest			$ 1,136,000		$ 624,000		$ 130,000

[1] Financial information for 2010, 2011, and 2012 has been revised to include results attributable to the Redbird Class A interests and the Blending and Packaging Assets acquired from Cross prior to October 2, 2012. See Note 2(a) – Principles of Presentation and Consolidation.

[2] Effective September 2010, the Partnership entered into an interest rate swap that swapped $40,000 of fixed rate to floating rate. The floating rate cost was the applicable three-month LIBOR rate. This interest rate swap was scheduled to mature in April 2018, but was terminated in August 2011.** Effective September 2010, the Partnership entered into an interest rate swap that swapped $60,000 of fixed rate to floating rate. The floating rate cost was the applicable three-month LIBOR rate. This interest rate swap was scheduled to mature in April 2018, but was terminated in August 2011.

[3] Pursuant to the Indenture under which the Senior Notes were issued, the Partnership has the option to redeem up to 35% of the aggregate principal amount at a redemption price of 108.875% of the principal amount, plus accrued and unpaid interest with the proceeds of certain equity offerings. On April 24, 2012, the Partnership notified the Trustee of its intention to exercise a partial redemption of the Partnership’s Senior Notes pursuant to the Indenture. On May 24, 2012, the Partnership redeemed $25,000 of the Senior Notes from various holders using proceeds of the Partnership’s January 2012 follow-on equity offering, which in the interim were used to pay down amounts outstanding under the Partnership’s revolving credit facility. In conjunction with the redemption, the Partnership incurred a debt prepayment premium in the amount of $2,219, which is included in the consolidated statement of operations for the year ended December 31, 2012.

[4] Interest rate fluctuates based on the LIBOR rate plus an applicable margin set on the date of each advance. The margin above LIBOR is set every three months. Indebtedness under the credit facility bears interest at LIBOR plus an applicable margin or the base prime rate plus an applicable margin. The applicable margin for revolving loans that are LIBOR loans ranges from 2.00% to 3.25% and the applicable margin for revolving loans that are base prime rate loans ranges from 1.00% to 2.25%. The applicable margin for existing LIBOR borrowings is 3.00%. Effective January 1, 2013, the applicable margin for existing LIBOR borrowings decreased to 2.25%. Effective April 1, 2013, the applicable margin for existing LIBOR borrowings will increase to 2.75%.

[5] Effective October 2008, the Partnership entered into a cash flow hedge that swapped $40,000 of floating rate to fixed rate. The fixed rate cost was 2.82% plus the Partnership’s applicable LIBOR borrowing spread. Effective April 2009, the Partnership entered into two subsequent swaps to lower its effective fixed rate to 2.58% plus the Partnership’s applicable LIBOR borrowing spread. These cash flow hedges were scheduled to mature in October 2010, but were terminated in March 2010.*** Effective January 2008, the Partnership entered into a cash flow hedge that swapped $25,000 of floating rate to fixed rate. The fixed rate cost was 3.40% plus the Partnership’s applicable LIBOR borrowing spread. Effective April 2009, the Partnership entered into two subsequent swaps to lower its effective fixed rate to 3.050% plus the Partnership’s applicable LIBOR borrowing spread. These cash flow hedges matured in January 2010.*** Effective September 2007, the Partnership entered into a cash flow hedge that swapped $25,000 of floating rate to fixed rate. The fixed rate cost was 4.61% plus the Partnership’s applicable LIBOR borrowing spread. Effective March 2009, the Partnership entered into two subsequent swaps to lower its effective fixed rate to 4.31% plus the Partnership’s applicable LIBOR borrowing spread. These cash flow hedges were scheduled to mature in September 2010, but were terminated in March 2010.*** Effective November 2006, the Partnership entered into an interest rate swap that swapped $30,000 of floating rate to fixed rate. The fixed rate cost was 4.77% plus the Partnership’s applicable LIBOR borrowing spread. This cash flow hedge matured in March 2010.*** Effective March 2006, the Partnership entered into a cash flow hedge that swapped $75,000 of floating rate to fixed rate. The fixed rate cost was 5.25% plus the Partnership’s applicable LIBOR borrowing spread. Effective February 2009, the Partnership entered into two subsequent swaps to lower its effective fixed rate to 5.10% plus the Partnership’s applicable LIBOR borrowing spread. These cash flow hedges were scheduled to mature in November 2010, but were terminated in March 2010.