Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Summary of Components of Company's Income Tax Provision (Benefit) from Continuing Operations

The following table presents the components of the Company’s income tax provision:

	Year Ended December 31,
	2020		2019		2018
	(In millions)
Current
U.S. federal	$	4.8	$	45.2	$	35.1
State and local	(0.1)		11.5		11.5
	4.7		56.7		46.6
Deferred
U.S. federal	26.1		(8.1)		0.9
State and local	11.7		2.3		3.8
	37.8		(5.8)		4.7
Income tax provision	$	42.5	$	50.9	$	51.3

Schedule of Reconciliation of U.S. Federal Statutory Income Tax Rate to Effective Income Tax Rate on Earnings

The following table presents the reconciling items between the income tax provision using the U.S. federal statutory rate and the Company's reported income tax provision.

	Year Ended December 31,
	2020		2019		2018
	(In millions)
Statutory U.S. federal income tax	$	37.9	$	40.3	$	39.6
State income taxes, net of federal benefit	9.1		10.9		12.1
Reserve adjustments	1.2		3.9		2.7
Tax credits and special deductions	(4.6)		(2.7)		(3.7)
Nondeductible compensation	3.4		1.0		0.8
Stock-based compensation excess tax benefits	(4.4)		(2.3)		(0.4)
Other	(0.1)		(0.2)		0.2
Income tax provision	$	42.5	$	50.9	$	51.3

The following table presents a reconciliation of the U.S. federal statutory income tax rate to the Company’s effective income tax rate on earnings in percentages.

	Year Ended December 31,
	2020		2019		2018
Statutory U.S. federal income tax rate	21.0	%	21.0	%	21.0	%
State income taxes, net of federal benefit	5.1		5.7		6.4
Reserve adjustments	0.7		2.0		1.4
Tax credits and special deductions	(2.6)		(1.4)		(2.0)
Nondeductible compensation	1.9		0.5		0.5
Stock-based compensation excess tax benefits	(2.4)		(1.2)		(0.2)
Other	(0.1)		(0.1)		0.1
Effective income tax rate	23.6	%	26.5	%	27.2	%

Schedule of Reconciliation of Change in Unrecognized Tax Benefits

The following table presents a reconciliation of unrecognized tax benefits:

	Year Ended December 31,
	2020		2019		2018
	(In millions)
Balances at beginning of year	$	58.0	$	7.4	$	4.4
Increases based on tax positions in prior years	2.7		40.4		0.3
Decreases based on tax position in prior years	(51.5)		—		(0.1)
Increases based on tax positions in current year	5.6		10.4		3.5
Lapse of statute of limitations	(0.6)		(0.2)		(0.7)
Balances at end of year	$	14.2	$	58.0	$	7.4

Summary of Deferred Tax Assets and Liabilities

The following table presents the deferred tax assets and liabilities:

	As of December 31,
	2020		2019
	(In millions)
Deferred Tax Assets
Accrued estimated costs	$	48.4	$	43.2
Basis difference in assets and liabilities	68.5		59.0
Operating lease liabilities	12.3		12.9
Tax losses and credit carryforwards	1.7		3.0
Net cumulative defined benefit pension plan losses	81.5		95.9
Retiree medical and life insurance benefits	6.0		6.2
Total deferred tax assets	218.4		220.2
Deferred Tax Liabilities
Revenue recognition differences	116.7		77.7
Basis differences in intangible assets	9.2		8.6
ROU assets	11.4		12.0
Total deferred tax liabilities	137.3		98.3
Total net deferred tax assets	$	81.1	$	121.9