Pension Plans and Other Postretirement Benefits (Details-2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Target allocation [Abstract]
Equity securities		63.00%
Debt securities		30.00%
Real estate		7.00%
Total		100.00%
United States equity		45.50%
Non-United States equity		17.50%
Percentage of Plan Assets [Abstract]
Equity securities		64.00%	68.00%
Debt securities		28.00%	26.00%
Real estate		8.00%	6.00%
Total		100.00%	100.00%
Concentration of risk [Abstract]
Concentration of risk		10.00%
Pension Benefits [Member]
Change in plan assets [Line Items]
Fair value of plan assets at beginning of year	$ 173,311	$ 159,354	$ 133,871
Actual return on plan assets		3,206	20,226
Employer contributions		19,215	12,985
Plan participants' contributions		0	0
Gross benefits paid		(8,464)	(7,728)
Fair value of plan assets at end of year		173,311	159,354	133,871
Long-term rate of return [Abstract]
Long-term rate of return	8.10%	8.25%	8.50%	8.50%
Postretirement Benefits [Member]
Change in plan assets [Line Items]
Fair value of plan assets at beginning of year	23,456	20,949	17,338
Actual return on plan assets		431	2,254
Employer contributions		4,472	3,559
Plan participants' contributions		626	569
Gross benefits paid		(3,022)	(2,771)
Fair value of plan assets at end of year		$ 23,456	$ 20,949	$ 17,338
Long-term rate of return [Abstract]
Long-term rate of return	7.26%	7.39%	7.44%	7.11%

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Target allocation percentage of investments in United States equity securities to total plan assets presented on a weighted-average basis as of the measurement date of the latest statement of financial position.

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Target allocation percentage of investments in non-United States equity securities to total plan assets presented on a weighted-average basis as of the measurement date of the latest statement of financial position.

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Target allocation percentage of total plan assets.

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The defined percentage of a particular investment of plan assets as a portion of the total plan assets at which a significant concentration is met.

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The difference between fair value of plan assets at the end of the period and the fair value at the beginning of the period, adjusted for contributions and payments of benefits during the period, and after adjusting for taxes and other expenses, as applicable.

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An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

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The increase in the fair value of plan assets from contributions made by the employer.

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Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

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The percentage of the fair value of real estate to the fair value of total plan assets held as of the measurement date.

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Target allocation percentage of investments in equity securities to total plan assets presented on a weighted-average basis as of the measurement date of the latest statement of financial position.

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Target allocation percentage of investments in real estate to total plan assets presented on a weighted-average basis as of the measurement date of the latest statement of financial position.

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