Employee Benefit Plans (Fair Value Measurement Levels For Qualified Plan Assets) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Cash	$ 323,975	$ 316,807
Short-term investments	564,364	757,162
Percent of equities mutual funds in US equities	90.00%	90.00%
Percent of equities mutual funds in international equities	10.00%	10.00%
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Short-term investments, which approximate fair value	14,328	10,590
Multi-strategy equity fund, fair value	10,629	10,765
Private equity limited partnerships	11,423	9,156
Total	157,090	152,446
Percent of fixed income funds in US securities	50.00%	50.00%
Percent of fixed income funds in international securities	50.00%	50.00%
Pension Benefits [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Short-term investments, which approximate fair value	14,328	10,590
Total	135,037	132,525
Pension Benefits [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Cash
Short-term investments, which approximate fair value
Multi-strategy equity fund, fair value
Private equity limited partnerships
Total
Pension Benefits [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Multi-strategy equity fund, fair value	10,629	10,765
Private equity limited partnerships	11,423	9,156
Total	22,053	19,921
Pension Benefits [Member] | Fixed Maturities [Member]
Defined Benefit Plan Disclosure [Line Items]
Mutual funds, fair value	23,948	24,630
Pension Benefits [Member] | Fixed Maturities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Mutual funds, fair value	23,948	24,630
Pension Benefits [Member] | Fixed Maturities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Mutual funds, fair value
Pension Benefits [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Mutual funds, fair value	96,762	97,305
Pension Benefits [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Mutual funds, fair value	96,762	97,305
Pension Benefits [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Mutual funds, fair value