Employee Benefit Plans (Fair Value Measurement Levels For Qualified Plan Assets) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Cash	$ 448,651		$ 258,408
Short-term investments, which approximates fair value	3,109	[1]	2,728	[1]
Multi-strategy equity fund, fair value	7,891	[2]	10,259	[2]
Private equity limited partnership	991
Total	101,304		114,470
Number of fixed income mutual funds	three
Number of equities mutual funds	eight
Ratio of equities mutual funds in US equities	75.00%
Ratio of equities mutual funds in international equities	25.00%
Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Mutual funds, fair value	33,573	[3]	35,334	[3]
Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Mutual funds, fair value	55,423	[4]	65,793	[4]
Cash Managed By Employee Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Cash	317		356
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Short-term investments, which approximates fair value	3,109	[1]	2,728	[1]
Total	92,422		104,211
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Mutual funds, fair value	33,573	[3]	35,334	[3]
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Mutual funds, fair value	55,423	[4]	65,793	[4]
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Cash Managed By Employee Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Cash	317		356
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Multi-strategy equity fund, fair value	7,891	[2]	10,259	[2]
Private equity limited partnership	991
Total	$ 8,882		$ 10,259

[1] This category includes high quality, short-term money market instruments, which are issued and payable in U.S. dollars.

[2] This category consists of a privately held fund of U.S. and international equity funds and may include currency hedges for the foreign funds. The fair value is provided by the external investment manager.

[3] This category includes three fixed income funds, which invest in investment grade securities of corporations, governments and government agencies with approximately half in U.S. securities and half in international securities.

[4] This category includes eight funds, which invest in small, mid and multi-cap equity securities including common stocks, securities convertible into common stock and securities with common stock characteristics, such as rights and warrants, with approximately three-fourths in U.S. equities and one-fourth in international equities.