Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Consolidated Statements of Comprehensive Income (Unaudited) [Abstract]
Net income per consolidated statements of income	$ 30,320	$ 24,013
Unrealized gains on available for sale securities:
Unrealized holding losses arising during the period	(1,916)	(946)
Less: adjustment for net gains realized in net income	(648)	(4)
Pension and other postretirement benefit plans:
Change in net actuarial loss during the period	980	753
Other comprehensive loss	(1,584)	(197)
Comprehensive income	$ 28,736	$ 23,816

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the reporting entity. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, but excludes any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

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-Glossary Comprehensive Income

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-Glossary Net Income

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-Glossary Other Comprehensive Income

-URI http://asc.fasb.org/extlink&oid=6519514

+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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-Number 210

-Section 04

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+ Details

- Definition

This element represents Other Comprehensive Income or Loss, Net of Tax, for the period attributable to the parent entity. Includes deferred gains or losses on qualifying hedges, unrealized holding gains or losses on available-for-sale securities, minimum pension liability, and cumulative translation adjustment.

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- Definition

Reclassification adjustment for unrealized gains or losses realized upon the sale of securities, after tax.

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- Definition

Appreciation or loss in value (before reclassification adjustment) of the total of unsold securities during the period being reported on, net of tax. Reclassification adjustments include: (1) the unrealized holding gain (loss), net of tax, at the date of the transfer for a debt security from the held-to-maturity category transferred into the available-for-sale category. Also includes the unrealized gain (loss) at the date of transfer for a debt security from the available-for-sale category transferred into the held-to-maturity category; (2) the unrealized gains (losses) realized upon the sale of securities, after tax; and (3) the unrealized gains (losses) realized upon the write-down of securities, after tax.

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+ Details