Employee Benefit Plans (Fair Value Measurement Levels For Qualified Plan Assets) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 item		Dec. 31, 2011 item
Defined Benefit Plan Disclosure [Line Items]
Cash	$ 347,720		$ 348,267
Number of fixed income mutual funds	3		3
Number of equities mutual funds	8		8
Number of private equity limited partnerships	2		1
Ratio of equities mutual funds in US equities	75.00%		75.00%
Ratio of equities mutual funds in international equities	25.00%		25.00%
Defined Benefit Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Cash			317
Short-term investments, which approximates fair value	3,343	[1]	3,109	[1]
Multi-strategy equity fund, fair value	9,092	[2]	7,891	[2]
Private equity limited partnership	5,524	[3]	991	[4]
Total	114,807		101,304
Defined Benefit Pension Plans [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Cash			317
Short-term investments, which approximates fair value	3,343	[1]	3,109	[1]
Total	100,191		92,422
Defined Benefit Pension Plans [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Cash
Short-term investments, which approximates fair value		[1]		[1]
Multi-strategy equity fund, fair value		[2]		[2]
Private equity limited partnership		[3]		[4]
Total
Defined Benefit Pension Plans [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Multi-strategy equity fund, fair value	9,092	[2]	7,891	[2]
Private equity limited partnership	5,524	[3]	991	[4]
Total	14,616		8,882
Defined Benefit Pension Plans [Member] | Fixed Maturities [Member]
Defined Benefit Plan Disclosure [Line Items]
Mutual funds, fair value	33,783	[5]	33,573	[5]
Defined Benefit Pension Plans [Member] | Fixed Maturities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Mutual funds, fair value	33,783	[5]	33,573	[5]
Defined Benefit Pension Plans [Member] | Fixed Maturities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Mutual funds, fair value		[5]		[5]
Defined Benefit Pension Plans [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Mutual funds, fair value	63,065	[6]	55,423	[6]
Defined Benefit Pension Plans [Member] | Equity Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Mutual funds, fair value	63,065	[6]	55,423	[6]
Defined Benefit Pension Plans [Member] | Equity Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Mutual funds, fair value		[6]		[6]

[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 consists of two private equity limited partnerships.

[4] This category consists of a private equity limited partnership.

[5] 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.

[6] 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.