Benefit Plans Benefit Plans - Allocation of Plan Assets (Details) (Pension Benefits [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 485,489		$ 450,632		$ 398,657
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Target Allocation Percentage of Assets, Equity Securities	45.00%
Target Allocation Percentage of Assets, Debt Securities	40.00%
Target Allocation Percentage of Assets, Real Estate	5.00%
Target Allocation Percentage of Assets, Other	10.00%
Target Allocation Percentage of Assets, Total	100.00%
Defined Benefit Plan, Actual Plan Asset Allocations [Abstract]
Equity securities	35.00%		45.00%
Debt securities	51.00%		43.00%
Real estate	4.00%		3.00%
Other	10.00%		9.00%
Total	100.00%		100.00%
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	135,430		100,361
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	283,461		293,496
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	66,598		56,775
Cash and other [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	50,389		55
Cash and other [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	50,389		55
Cash and other [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
Cash and other [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
Multi-strategy hedge funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	26,605	[1]	22,107	[1]
Multi-strategy hedge funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	[1]	0	[1]
Multi-strategy hedge funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	[1]	0	[1]
Multi-strategy hedge funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	26,605	[1]	22,107	[1]
Private equity funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	23,550	[2]	20,488	[2]
Private equity funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	[2]	0	[2]
Private equity funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	[2]	0	[2]
Private equity funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	23,550	[2]	20,488	[2]
U.S. mid growth [Member] | Mutual funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	15,771		18,240
U.S. mid growth [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	15,771		18,240
U.S. mid growth [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
U.S. mid growth [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
U.S. mid cap value [Member] | Equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	14,672		16,640
U.S. mid cap value [Member] | Equity securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	14,672		16,640
U.S. mid cap value [Member] | Equity securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
U.S. mid cap value [Member] | Equity securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
U.S. small cap core [Member] | Equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	17,253		21,610
U.S. small cap core [Member] | Equity securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	17,253		21,610
U.S. small cap core [Member] | Equity securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
U.S. small cap core [Member] | Equity securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
International developed markets [Member] | Equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	37,345		43,816
International developed markets [Member] | Equity securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	37,345		43,816
International developed markets [Member] | Equity securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
International developed markets [Member] | Equity securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
U.S. corporate bonds [Member] | Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	68,356		68,108
U.S. corporate bonds [Member] | Fixed income securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
U.S. corporate bonds [Member] | Fixed income securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	68,356		68,108
U.S. corporate bonds [Member] | Fixed income securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
International corporate bonds [Member] | Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2,316		2,568
International corporate bonds [Member] | Fixed income securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
International corporate bonds [Member] | Fixed income securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2,316		2,568
International corporate bonds [Member] | Fixed income securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
U.S. government [Member] | Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	3,436		734
U.S. government [Member] | Fixed income securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0
U.S. government [Member] | Fixed income securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	3,436		734
Other fixed income [Member] | Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	598		1,982
Other fixed income [Member] | Fixed income securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
Other fixed income [Member] | Fixed income securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	598		1,982
Other fixed income [Member] | Fixed income securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
Emerging markets [Member] | Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	17,334		25,666
Emerging markets [Member] | Fixed income securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
Emerging markets [Member] | Fixed income securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	17,334		25,666
Emerging markets [Member] | Fixed income securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0		0
Real estate [Member] | Common collective trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	16,443	[3]	14,180	[3]
Real estate [Member] | Common collective trusts [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	[3]	0	[3]
Real estate [Member] | Common collective trusts [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	[3]	0	[3]
Real estate [Member] | Common collective trusts [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	16,443	[3]	14,180	[3]
Other [Member] | Common collective trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	191,421	[4]	194,438	[4]
Other [Member] | Common collective trusts [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	[4]	0	[4]
Other [Member] | Common collective trusts [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	191,421	[4]	194,438	[4]
Other [Member] | Common collective trusts [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 0	[4]	$ 0	[4]

[1] Multi-strategy hedge funds The objective of the multi-strategy hedge funds is to diversify risks and reduce volatility. At December 31, 2011 and 2010, investments in this class include approximately 35 percent long/short equity, 35 percent arbitrage and event investments and 30 percent in directional trading, fixed income and other. Investments in the multi-strategy hedge fund can be redeemed semi-annually with a 95-day notice.

[2] Private equity funds The objective of the private equity funds is to achieve long-term returns through investments in a diversified portfolio of private equity limited partnerships that offer a variety of investment strategies, targeting low volatility and low correlation to traditional asset classes. As of December 31, 2011 and 2010, investments in these private equity funds include approximately 50 percent and 45 percent, respectively, in buyout private equity funds that usually invest in mature companies with established business plans, 30 percent and 35 percent, respectively, in special situations private equity and debt funds that focus on niche investment strategies and 20 percent in both years, in venture private equity funds that invest in early development or expansion of business. Investments in the private equity fund can be redeemed only with written consent from the general partner, which may or may not be granted. At December 31, 2011 and 2010, the Company had unfunded commitments of underlying funds of $5,618 and $6,012.

[3] Real estate common collective trust The objective of the real estate common collective trust (CCT) is to achieve long-term returns through investments in a broadly diversified portfolio of improved properties with stabilized occupancies. As of December 31, 2011, investments in this CCT include approximately 46 percent office, 23 percent residential, 19 percent retail and 12 percent industrial, cash and other. As of December 31, 2010 investments in this CCT include approximately 33 percent office, 21 percent residential, 23 percent retail and 23 percent industrial, cash and other. Investments in the real estate CCT can be redeemed once per quarter subject to available cash, with a 45-day notice.

[4] Other common collective trusts At December 31, 2011, approximately 64 percent of the other CCTs are invested in fixed income securities including approximately 35 percent in mortgage-backed securities, 43 percent in corporate bonds and 20 percent in U.S. Treasury and other. Approximately 36 percent of the other CCTs at December 31, 2011 are invested in Russell 1000 Fund large cap index funds. At December 31, 2010, approximately 61 percent of the other CCTs are invested in fixed-income securities including approximately 40 percent in mortgage-backed securities, 35 percent in corporate bonds and 25 percent in U.S. Treasury and other. Approximately 39 percent of the other CCTs at December 31, 2010 are invested in Russell 1000 Fund large cap index funds. Investments in fixed-income securities can be redeemed daily.