Employee Benefits Plans (Details 6) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Level 3 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	$ 71,207	$ 68,543	$ 17,745
Pension Benefits [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	1,612,927	1,418,042	1,428,784
Pension Benefits [Member] | Level 1 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	76,660	63,069
Pension Benefits [Member] | Level 2 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	1,465,060	1,286,430
Pension Benefits [Member] | Level 3 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	71,207	68,543
Pension Benefits [Member] | Private equity and hedge funds [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	71,207	68,543
Pension Benefits [Member] | Private equity and hedge funds [Member] | Level 1 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	0	0
Pension Benefits [Member] | Private equity and hedge funds [Member] | Level 2 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	0	0
Pension Benefits [Member] | Private equity and hedge funds [Member] | Level 3 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	71,207	68,543
Pension Benefits [Member] | Equity securities [Member] | U.S. companies [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	76,660	63,069
Pension Benefits [Member] | Equity securities [Member] | U.S. companies [Member] | Level 1 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	76,660	63,069
Pension Benefits [Member] | Equity securities [Member] | U.S. companies [Member] | Level 2 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	0	0
Pension Benefits [Member] | Equity securities [Member] | U.S. companies [Member] | Level 3 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	0	0
Pension Benefits [Member] | Equity securities [Member] | U.S. mutual funds [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	471,504	500,298
Pension Benefits [Member] | Equity securities [Member] | U.S. mutual funds [Member] | Level 1 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	0	0
Pension Benefits [Member] | Equity securities [Member] | U.S. mutual funds [Member] | Level 2 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	471,504	500,298
Pension Benefits [Member] | Equity securities [Member] | U.S. mutual funds [Member] | Level 3 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	0	0
Pension Benefits [Member] | Equity securities [Member] | Foreign mutual funds [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	497,315	337,185
Pension Benefits [Member] | Equity securities [Member] | Foreign mutual funds [Member] | Level 1 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	0	0
Pension Benefits [Member] | Equity securities [Member] | Foreign mutual funds [Member] | Level 2 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	497,315	337,185
Pension Benefits [Member] | Equity securities [Member] | Foreign mutual funds [Member] | Level 3 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	0	0
Pension Benefits [Member] | Fixed income securities [Member] | Corporate bonds [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	61,571	53,424
Pension Benefits [Member] | Fixed income securities [Member] | Corporate bonds [Member] | Level 1 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	0	0
Pension Benefits [Member] | Fixed income securities [Member] | Corporate bonds [Member] | Level 2 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	61,571	53,424
Pension Benefits [Member] | Fixed income securities [Member] | Corporate bonds [Member] | Level 3 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	0	0
Pension Benefits [Member] | Fixed income securities [Member] | Mutual funds [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	434,670	394,714
Pension Benefits [Member] | Fixed income securities [Member] | Mutual funds [Member] | Level 1 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	0	0
Pension Benefits [Member] | Fixed income securities [Member] | Mutual funds [Member] | Level 2 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	434,670	394,714
Pension Benefits [Member] | Fixed income securities [Member] | Mutual funds [Member] | Level 3 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets	0	0
Pension Benefits [Member] | Fixed income securities [Member] | Other Securities [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets		809
Pension Benefits [Member] | Fixed income securities [Member] | Other Securities [Member] | Level 1 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets		0
Pension Benefits [Member] | Fixed income securities [Member] | Other Securities [Member] | Level 2 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets		809
Pension Benefits [Member] | Fixed income securities [Member] | Other Securities [Member] | Level 3 [Member]
Fair value of each major category of pension plan assets and the level of inputs used to measure fair value
Fair Value of Plan Assets		$ 0