Pension and Postretirement Plans (Fair Value of Pension Plan Assets) (Details 10) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	$ 2,042,490	$ 2,234,268	$ 2,469,968
Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	2,042,490	2,234,268
Cash equivalents and other short-term investments [Member] | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	223,448	290,273
Equity securities [Member] | Fair Value, Measurements, Recurring [Member] | U.S. [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	1,074,528	1,378,158
Equity securities [Member] | Fair Value, Measurements, Recurring [Member] | International [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	120,735	564,263
Equity funds [Member] | Fair Value, Measurements, Recurring [Member] | U.S. [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	622,865
Total investments [Member] | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	2,041,576	2,232,694
Receivables [Member] | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	914	1,574
Level 1 [Member] | Cash equivalents and other short-term investments [Member] | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	61,438	256,364
Level 1 [Member] | Equity securities [Member] | Fair Value, Measurements, Recurring [Member] | U.S. [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	1,074,528	1,378,158
Level 1 [Member] | Equity securities [Member] | Fair Value, Measurements, Recurring [Member] | International [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	120,735	564,263
Level 1 [Member] | Equity funds [Member] | Fair Value, Measurements, Recurring [Member] | U.S. [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0
Level 1 [Member] | Total investments [Member] | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	1,256,701	2,198,785
Level 2 [Member] | Cash equivalents and other short-term investments [Member] | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	162,010	33,909
Level 2 [Member] | Equity securities [Member] | Fair Value, Measurements, Recurring [Member] | U.S. [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 2 [Member] | Equity securities [Member] | Fair Value, Measurements, Recurring [Member] | International [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 2 [Member] | Equity funds [Member] | Fair Value, Measurements, Recurring [Member] | U.S. [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0
Level 2 [Member] | Total investments [Member] | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	162,010	33,909
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	622,865	$ 0
Level 3 [Member] | Cash equivalents and other short-term investments [Member] | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0
Level 3 [Member] | Equity securities [Member] | Fair Value, Measurements, Recurring [Member] | U.S. [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0
Level 3 [Member] | Equity securities [Member] | Fair Value, Measurements, Recurring [Member] | International [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0
Level 3 [Member] | Equity funds [Member] | Fair Value, Measurements, Recurring [Member] | U.S. [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	622,865
Level 3 [Member] | Total investments [Member] | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	$ 622,865