Benefit Plans Benefit Plans - Allocation of Plan Assets (Details) (Pension Benefits, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage	100.00%
Actual Allocation Percentage	100.00%		100.00%
Reduction to plan assets for anticipated lump sum payments in next fiscal year	$ 15,817		$ 15,817
Fair value of plan assets	364,205	[1]	346,560	473,097
Fair value of plan assets at end of year, prior to reduction for anticipated distributions			362,377
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	85,475
Fair value of plan assets at end of year, prior to reduction for anticipated distributions			92,381
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	224,590
Fair value of plan assets at end of year, prior to reduction for anticipated distributions			196,570
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	54,140
Fair value of plan assets at end of year, prior to reduction for anticipated distributions			73,426
Cash and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,883		20,884
Cash and other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,883		20,884
Multi-strategy hedge funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16,593		22,637
Multi-strategy hedge funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16,593		22,637
Private equity funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	20,779		21,627
Private equity funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	20,779		21,627
Balanced fund | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15,291		13,477
Balanced fund | Mutual funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15,291		13,477
U.S. mid cap value | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13,949		12,325
U.S. mid cap value | Equity securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13,949		12,325
U.S. small cap core | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18,477		15,368
U.S. small cap core | Equity securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18,477		15,368
International developed markets | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	33,875		30,327
International developed markets | Equity securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	33,875		30,327
U.S. corporate bonds | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	51,671		37,414
U.S. corporate bonds | Fixed income securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	51,671		37,414
International corporate bonds | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	217		850
International corporate bonds | Fixed income securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	217		850
U.S. government | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,948		3,358
U.S. government | Fixed income securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,948		3,358
Other fixed income | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	271		893
Other fixed income | Fixed income securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	271		893
Emerging markets | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16,730		14,335
Emerging markets | Fixed income securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16,730		14,335
Real estate | Common collective trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16,768		29,162
Real estate | Common collective trusts [Member] | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16,768		29,162
Other | Common collective trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	153,753		139,720
Other | Common collective trusts [Member] | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 153,753		$ 139,720
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage	45.00%
Actual Allocation Percentage	45.00%		41.00%
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage	40.00%
Actual Allocation Percentage	40.00%		33.00%
Real estate
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage	5.00%
Actual Allocation Percentage	5.00%		8.00%
Other
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage	10.00%
Actual Allocation Percentage	10.00%		18.00%

[1] The fair value of plan assets as of December 31, 2013 reflects distributions of $15,817 paid in 2014 related to the Company's voluntary early retirement program