Unaudited Condensed Consolidated Statement of Changes in Stockholders' Equity Unaudited Condensed Consolidated Statement of Changes in Stockholders' Equity (Parenthetical) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Postretirement plans and workers' compensation obligations, tax provision	$ 0.0	$ 0.0
Retained earnings
Dividends declared per share	$ 0.000	$ 1.980
Total Accumulated Other Comprehensive Income
Postretirement plans and workers' compensation obligations, tax provision	$ 0.0	$ 0.0

Amount, after reclassification adjustment, of tax (expense) benefit for (increase) decrease in accumulated other comprehensive income of defined benefit plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
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