Pension and Postretirement Plans (Fair Value of Pension Plan Assets) (Details 9) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	$ 2,120,127	$ 2,343,471	$ 2,042,490
Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	2,120,127	2,343,471
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	271,612	255,515
U.S. equities | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	1,115,323	1,242,139
International equities | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	131,912	138,640
U.S. stock index fund [Member] | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	601,395	706,202
Total investments [Member] | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	2,120,242	2,342,496
Receivables (Payables) for settlement of investments purchased, net [Member] | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	(115)	975
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	2,068	73,877
Level 1 [Member] | U.S. equities | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	1,115,323	1,242,139
Level 1 [Member] | International equities | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	131,912	138,640
Level 1 [Member] | U.S. stock index fund [Member] | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	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	1,249,303	1,454,656
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	269,544	181,638
Level 2 [Member] | U.S. equities | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 2 [Member] | International equities | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 2 [Member] | U.S. stock index fund [Member] | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	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	269,544	181,638
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	601,395	706,202	$ 622,865
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	0
Level 3 [Member] | U.S. equities | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 3 [Member] | International equities | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	0
Level 3 [Member] | U.S. stock index fund [Member] | Fair Value, Measurements, Recurring [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	601,395	706,202
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	$ 601,395	$ 706,202