13.	Income taxes

The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse.

Income tax expense (benefit) consisted of the following:

	Year ended December 31,
	2015			2014		2013
Current:
Federal	$	183,263		$	188,302	$	334,258
State		30,766			30,789		68,715
International		856			1,687		1,764
Total current income tax	$	214,885		$	220,778	$	404,737
Deferred:
Federal		88,718			192,267		(6,695	)
State		(8,307	)		32,360		(8,941	)
International		430			938		746
Total deferred income tax	$	80,841		$	225,565	$	(14,890	)
	$	295,726		$	446,343	$	389,847

The allocation of income tax expense (benefit) was as follows:

	Year ended December 31,
	2015		2014		2013
Continuing operations	$	295,726	$	446,343	$	381,013
Discontinued operations		—		—		(84	)
Gain on discontinued operations		—		—		8,918
	$	295,726	$	446,343	$	389,847

The reconciliation between the Company’s effective tax rate from continuing operations and the U.S. federal income tax rate is as follows:

	Year ended December 31,
	2015			2014			2013
Federal income tax rate		35.0	%		35.0	%		35.0	%
State income taxes, net of federal benefit		2.5			3.5			3.8
International rate differential		(1.1	)		(0.2	)		0.1
Goodwill and intangible impairments		11.7			—			—
Changes in deferred tax valuation allowances		2.6			0.6			0.3
Contingent earn-out adjustments		—			—			(2.6	)
Other		1.5			(0.8	)		1.4
Impact of noncontrolling interests primarily attributable to non-tax paying entities		(11.3	)		(4.0	)		(4.1	)
Effective tax rate		40.9	%		34.1	%		33.9	%

The Company has not recognized any deferred taxes for the undistributed earnings of its foreign subsidiaries because the Company currently expects those earnings to be permanently reinvested. Determination of the amount of unrecognized deferred taxes related to undistributed earnings of foreign subsidiaries is not practicable because such liability, if any, is dependent on circumstances that will exist if and when remittance occurs.

Deferred tax assets and liabilities arising from temporary differences were as follows:

	December 31,
	2015			2014
Receivables	$	43,393		$	42,976
Accrued liabilities		272,080			253,228
Net operating loss carryforwards		130,977			102,212
Other		114,805			93,567
Deferred tax assets		561,255			491,983
Valuation allowance		(57,811	)		(28,784	)
Net deferred tax assets		503,444			463,199
Intangible assets		(927,761	)		(839,824	)
Property and equipment		(205,071	)		(187,198	)
Investments in partnerships		(83,584	)		(78,619	)
Other		(13,990	)		(7,633	)
Deferred tax liabilities		(1,230,406	)		(1,113,274	)
Net deferred tax liabilities	$	(726,962	)	$	(650,075	)

At December 31, 2015, the Company had federal net operating loss carryforwards of approximately $182,200 that expire through 2035, although a substantial amount expire by 2028. The Company also had state net operating loss carryforwards of $761,686 that expire through 2035 and international net operating loss carryforwards of $96,847, some of which have an indefinite life. The utilization of a portion of these losses may be limited in future years based on the profitability of certain entities. The valuation allowance increase of $29,027 is primarily due to the realizability of losses in certain foreign and state jurisdictions.

Unrecognized tax benefits

A reconciliation of the beginning and ending liability for unrecognized tax benefits that do not meet the more-likely-than-not threshold were as follows:

	Year ended December 31,
		2015			2014
Balance beginning	$	31,877		$	60,538
Additions for tax positions related to current year		6,131			914
Additions (reductions) for tax positions related to prior years		2,999			(27,312	)
Reductions related to lapse of applicable statute		(1,996	)		(2,077	)
Reductions related to settlements with taxing authorities		—			(186	)
Balance ending	$	39,011		$	31,877

As of December 31, 2015, the Company’s total liability for unrecognized tax benefits relating to tax positions that do not meet the more-likely-than-not threshold is $39,011, all of which would impact the Company’s effective tax rate if recognized. This balance represents an increase of $7,134 from the December 31, 2014 balance of $31,877.

The Company recognizes accrued interest and penalties related to unrecognized tax benefits in its income tax expense. At December 31, 2015 and 2014, the Company had approximately $9,918 and $10,123, respectively, accrued for interest and penalties related to unrecognized tax benefits, net of federal tax benefit.

The Company and its subsidiaries file U.S. federal and state income tax returns and various international income tax returns. The Company is no longer subject to U.S. federal and state examinations by tax authorities for years before 2011 and 2008, respectively.