Benefit Plans and Other Postretirement Benefits (Details 4) (Pension Benefits, USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure
Fair value of pension plan assets	$ 392,538	$ 334,423	$ 295,054
Equity securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	254,968	208,235
U.S. equities - large cap
Defined Benefit Plan Disclosure
Fair value of pension plan assets	122,127	93,047
U.S. equities - small/mid cap and other
Defined Benefit Plan Disclosure
Fair value of pension plan assets	24,738	25,159
International equities - growth
Defined Benefit Plan Disclosure
Fair value of pension plan assets	51,756	42,057
International equities - other
Defined Benefit Plan Disclosure
Fair value of pension plan assets	56,347	47,972
Fixed income securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	126,371	123,315
U.S. fixed income securities - intermediate term
Defined Benefit Plan Disclosure
Fair value of pension plan assets	62,182	59,983
U.S. fixed income securities - high yield
Defined Benefit Plan Disclosure
Fair value of pension plan assets	24,451	22,409
International fixed income securities - other
Defined Benefit Plan Disclosure
Fair value of pension plan assets	39,738	40,923
Cash and cash equivalents
Defined Benefit Plan Disclosure
Fair value of pension plan assets	11,199	2,873
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure
Fair value of pension plan assets	228,258	181,857
Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	154,557	119,001
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. equities - large cap
Defined Benefit Plan Disclosure
Fair value of pension plan assets	93,053	71,668
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. equities - small/mid cap and other
Defined Benefit Plan Disclosure
Fair value of pension plan assets	1,617
Quoted Prices in Active Markets for Identical Assets (Level 1) | International equities - growth
Defined Benefit Plan Disclosure
Fair value of pension plan assets	51,756	42,057
Quoted Prices in Active Markets for Identical Assets (Level 1) | International equities - other
Defined Benefit Plan Disclosure
Fair value of pension plan assets	8,131	5,276
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed income securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	62,502	59,983
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. fixed income securities - intermediate term
Defined Benefit Plan Disclosure
Fair value of pension plan assets	62,182	59,983
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. fixed income securities - high yield
Defined Benefit Plan Disclosure
Fair value of pension plan assets	320
Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash and cash equivalents
Defined Benefit Plan Disclosure
Fair value of pension plan assets	11,199	2,873
Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Fair value of pension plan assets	164,280	152,566
Significant Observable Inputs (Level 2) | Equity securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	100,411	89,234
Significant Observable Inputs (Level 2) | U.S. equities - large cap
Defined Benefit Plan Disclosure
Fair value of pension plan assets	29,074	21,379
Significant Observable Inputs (Level 2) | U.S. equities - small/mid cap and other
Defined Benefit Plan Disclosure
Fair value of pension plan assets	23,121	25,159
Significant Observable Inputs (Level 2) | International equities - other
Defined Benefit Plan Disclosure
Fair value of pension plan assets	48,216	42,696
Significant Observable Inputs (Level 2) | Fixed income securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	63,869	63,332
Significant Observable Inputs (Level 2) | U.S. fixed income securities - high yield
Defined Benefit Plan Disclosure
Fair value of pension plan assets	24,131	22,409
Significant Observable Inputs (Level 2) | International fixed income securities - other
Defined Benefit Plan Disclosure
Fair value of pension plan assets	$ 39,738	$ 40,923