Employee Benefit Plans (Details 3) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets	$ 60,303
Percentage of the Partnership's pension plan assets, Total	100.00%
Corporate and U.S. government bond fund (1) [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets	33,377
Percentage of the Partnership's pension plan assets, Total	55.00%
U.S. government and agency debt securities (1) [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets	2,707
Percentage of the Partnership's pension plan assets, Total	4.00%
U.S. large-cap equity (1) [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets	17,967
Percentage of the Partnership's pension plan assets, Total	30.00%
International equity (1) [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets	5,938
Percentage of the Partnership's pension plan assets, Total	10.00%
Cash [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets	314
Percentage of the Partnership's pension plan assets	1.00%
Level 1 [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets	60,303
Level 1 [Member] | Corporate and U.S. government bond fund (1) [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets	33,377
Level 1 [Member] | U.S. government and agency debt securities (1) [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets	2,707
Level 1 [Member] | U.S. large-cap equity (1) [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets	17,967
Level 1 [Member] | International equity (1) [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets	5,938
Level 1 [Member] | Cash [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets	314
Level 2 [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets
Level 2 [Member] | Corporate and U.S. government bond fund (1) [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets
Level 2 [Member] | U.S. government and agency debt securities (1) [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets
Level 2 [Member] | U.S. large-cap equity (1) [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets
Level 2 [Member] | International equity (1) [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets
Level 2 [Member] | Cash [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets
Level 3 [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets
Level 3 [Member] | Corporate and U.S. government bond fund (1) [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets
Level 3 [Member] | U.S. government and agency debt securities (1) [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets
Level 3 [Member] | U.S. large-cap equity (1) [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets
Level 3 [Member] | International equity (1) [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets
Level 3 [Member] | Cash [Member]
The fair values and percentage of the Partnership's pension plan assets by asset category
Fair values of the Partnership's pension plan assets