Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

Income Tax Disclosure [Abstract]

Components of Income Tax Expense (Benefit)

Components of income tax expense/(benefit) are as follows (amounts in thousands):

	Year Ended December 31,
	2015			2014		2013
Current
Federal	$	363,734		$	248,172	$	256,545
Foreign		3,151			4,167		1,655
State		38,987			23,224		28,490
		405,872			275,563		286,690
Deferred
Federal		(15,912	)		41,583		25,341
Foreign		5,545			—		—
State		(302	)		7,525		3,278
		(10,669	)		49,108		28,619
Total	$	395,203		$	324,671	$	315,309

Components of Deferred Taxes

The components of deferred taxes are as follows (amounts in thousands):

	Year Ended December 31,
	2015			2014
Deferred income tax assets:
Self-insurance reserves	$	88,401		$	84,915
Compensation accruals		66,399			55,788
State and foreign net operating loss carryforwards and    other state and foreign deferred tax assets		62,541			60,521
Other currently non-deductible accrued liabilities		17,213			16,739
Net pension liability—OCI only		10,929			11,746
Doubtful accounts and other reserves		29,616			18,428
Other combined items—OCI only		457			2,615
		275,556			250,752
Less: Valuation Allowance		(52,567	)		(52,764	)
Net deferred income tax assets:		222,989			197,988
Deferred income tax liabilities:
Depreciable and amortizable assets		(400,809	)		(362,674	)
Other deferred tax liabilities		(2,960	)		(2,963	)
Net deferred income tax liabilities	$	(180,780	)	$	(167,649	)

Effective Tax Rates Calculation

The effective tax rates, as calculated by dividing the provision for income taxes by income before income taxes, were as follows for each of the years ended December 31, 2015, 2014 and 2013 (dollar amounts in thousands):

	2015			2014			2013
Provision for income taxes	$	395,203		$	324,671		$	315,309
Income before income taxes		1,145,901			929,667			869,332
Effective tax rate		34.5	%		34.9	%		36.3	%

Reconciliation Between Federal Statutory Rate and Effective Tax Rate

A reconciliation between the federal statutory rate and the effective tax rate is as follows:

	Year Ended December 31,
	2015			2014			2013
Federal statutory rate		35.0	%		35.0	%		35.0	%
State taxes, net of federal income tax benefit		2.3	%		2.3	%		2.5	%
Divestiture gain		0.0	%		0.0	%		0.3	%
Other items		-0.6	%		0.0	%		0.4	%
Impact of income attributable to noncontrolling interests		-2.2	%		-2.4	%		-1.9	%
Effective tax rate		34.5	%		34.9	%		36.3	%

Net Deferred Tax Assets and Liabilities

The net deferred tax assets and liabilities are comprised as follows (amounts in thousands):

	Year Ended December 31,
	2015			2014
Current deferred taxes
Assets	$	135,120		$	115,870
Liabilities		—			(1,305	)
Total deferred taxes-current		135,120			114,565
Noncurrent deferred taxes
Assets		92,383			85,792
Liabilities		(408,283	)		(368,006	)
Total deferred taxes-noncurrent		(315,900	)		(282,214	)
Total deferred tax liabilities	$	(180,780	)	$	(167,649	)

Reconciliation of Unrecognized Tax Benefits

The tabular reconciliation of unrecognized tax benefits for the years ended December 31, 2015, 2014 and 2013 is as follows (amounts in thousands).

	As of  December 31,
	2015			2014			2013
Balance at January 1,	$	2,402		$	3,369		$	6,824
Additions based on tax positions related to the current year		50			50			50
Additions for tax positions of prior years		111			195			283
Reductions for tax positions of prior years		(524	)		(1,212	)		(1,260	)
Settlements		(57	)		—			(2,528	)
Balance at December 31,	$	1,982		$	2,402		$	3,369