Benefit Plans Benefit Plans (Detail 12) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Rollforward of Activity for Level 3 Asset Categories [Roll Forward]
Fair Value of Plan Assets, Ending	$ 753,030	$ 764,164
Level 3
Rollforward of Activity for Level 3 Asset Categories [Roll Forward]
Fair Value of Plan Assets, Beginning	93,035	43,386
Defined Benefit Plan, Actual Return on Plan Assets Still Held	4,394	(4,481)
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	115	103
Defined Benefit Plan, Purchases, Sales, and Settlements	20,157	49,349
Foreign Currency Exchange Rate Changes, Plan Assets	(1,208)	4,678
Fair Value of Plan Assets, Ending	116,493	93,035
Other Types of Investments, Multi-Strategy Fund of Hedge Funds
Rollforward of Activity for Level 3 Asset Categories [Roll Forward]
Fair Value of Plan Assets, Ending	78,650	56,398
Other Types of Investments, Multi-Strategy Fund of Hedge Funds | Level 3
Rollforward of Activity for Level 3 Asset Categories [Roll Forward]
Fair Value of Plan Assets, Beginning	56,398	23,064
Defined Benefit Plan, Actual Return on Plan Assets Still Held	2,704	(3,675)
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	112	308
Defined Benefit Plan, Purchases, Sales, and Settlements	20,606	34,239
Foreign Currency Exchange Rate Changes, Plan Assets	(1,170)	2,462
Fair Value of Plan Assets, Ending	78,650	56,398
Other Types of Investments, Equity Long/Short Fund of Hedge Funds [Member] | Level 3
Rollforward of Activity for Level 3 Asset Categories [Roll Forward]
Fair Value of Plan Assets, Beginning	0	5,299
Defined Benefit Plan, Actual Return on Plan Assets Still Held	0	0
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0	(206)
Defined Benefit Plan, Purchases, Sales, and Settlements	0	(5,450)
Foreign Currency Exchange Rate Changes, Plan Assets	0	357
Fair Value of Plan Assets, Ending	0	0
Real Asset Mutual Funds, Commodities
Rollforward of Activity for Level 3 Asset Categories [Roll Forward]
Fair Value of Plan Assets, Ending	50,656	33,718
Real Asset Mutual Funds, Commodities | Level 3
Rollforward of Activity for Level 3 Asset Categories [Roll Forward]
Fair Value of Plan Assets, Beginning	20,836	0
Defined Benefit Plan, Actual Return on Plan Assets Still Held	987	(720)
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0	0
Defined Benefit Plan, Purchases, Sales, and Settlements	0	20,874
Foreign Currency Exchange Rate Changes, Plan Assets	(7)	682
Fair Value of Plan Assets, Ending	21,816	20,836
Fixed Income Mutual Funds, Insurance Contracts
Rollforward of Activity for Level 3 Asset Categories [Roll Forward]
Fair Value of Plan Assets, Ending	16,869	15,968
Fixed Income Mutual Funds, Insurance Contracts | Level 3
Rollforward of Activity for Level 3 Asset Categories [Roll Forward]
Fair Value of Plan Assets, Beginning	1,556	2,114
Defined Benefit Plan, Actual Return on Plan Assets Still Held	34	(86)
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	3	1
Defined Benefit Plan, Purchases, Sales, and Settlements	114	(314)
Foreign Currency Exchange Rate Changes, Plan Assets	(46)	(159)
Fair Value of Plan Assets, Ending	1,661	1,556
Other Types of Investments, Convertible Preferred Equity Certificates
Rollforward of Activity for Level 3 Asset Categories [Roll Forward]
Fair Value of Plan Assets, Ending	14,366	14,245
Other Types of Investments, Convertible Preferred Equity Certificates | Level 3
Rollforward of Activity for Level 3 Asset Categories [Roll Forward]
Fair Value of Plan Assets, Beginning	14,245	12,909
Defined Benefit Plan, Actual Return on Plan Assets Still Held	669	0
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0	0
Defined Benefit Plan, Purchases, Sales, and Settlements	(563)	0
Foreign Currency Exchange Rate Changes, Plan Assets	15	1,336
Fair Value of Plan Assets, Ending	$ 14,366	$ 14,245