Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Reconciliations of statutory U.S. federal income tax rates to our effective tax rate

Reconciliations of the statutory U.S. federal income tax rates to our effective tax rate for continuing operations follow:

	Years Ended December 31,
	2018		2017		2016
Statutory rate	21.0	%	35.0	%	35.0	%
Tax reform	(0.3	)	3.1		—
State tax, net of federal benefit	3.8		2.6		3.1
Reverse federal impact of indemnification adjustments	3.5		2.5		(0.7	)
Unrecognized tax benefits, U.S. federal and state, net of federal benefit	(15.9	)	(2.0	)	1.6
Excess tax benefits/deficiencies for employee stock-based compensation, federal and state, net of federal benefit	(0.6	)	(1.7	)	—
Impact of state rate change on net deferred tax liabilities, net of federal benefit	(0.4	)	0.6		(0.5	)
State, valuation allowance adjustments on net operating losses	0.4		0.2		1.0
Other, net	1.4		0.9		0.1
Effective tax rate	12.9	%	41.2	%	39.6	%

Components of provision for income tax expense (benefit)

Income tax expense consists of:

	December 31,
	2018			2017			2016
Current provision:
Federal	$	102,516		$	248,191		$	228,505
State	32,638			13,092			24,336
Total current provision	135,154			261,283			252,841
Deferred (benefit)/provision:
Federal	(57,076		)	(58,124		)	(89,518		)
State	(6,225		)	(628		)	786
Total deferred benefit	(63,301		)	(58,752		)	(88,732		)
Provision for income tax expense	$	71,853		$	202,531		$	164,109

Schedule of deferred tax assets and liabilities

The tax effect of temporary differences that give rise to deferred tax assets and liabilities is summarized below.

	December 31,
	2018		2017
Deferred tax assets:
Loan reserves	$	85,100	$	62,603
Stock-based compensation plans	9,312		10,216
Deferred revenue	1,081		782
Operating loss carryovers	—		4,186
Accrued expenses not currently deductible	12,896		5,356
Unrecorded tax benefits	5,106		3,781
Market value adjustments on student loans, investments and derivatives	1,460		1,974
Other	953		436
Total deferred tax assets	115,908		89,334
Deferred tax liabilities:
Gains on repurchased debt	—		40,175
Fixed assets	7,150		5,303
Acquired intangible assets	5,179		4,595
Unrealized gains	3,436		1,104
Federal deferred for state receivable	2,083		3,584
Student loan premiums and discounts, net	1,971		1,051
Other	285		298
Total deferred tax liabilities	20,104		56,110
Net deferred tax assets	$	95,804	$	33,224

Summary of changes in unrecognized tax benefits

The following table summarizes changes in unrecognized tax benefits:

	December 31,
	2018			2017			2016
Unrecognized tax benefits at beginning of year	$	131,608		$	152,581		$	47,109
Increases resulting from tax positions taken during a prior period	4,121			7,482			110,894
Decreases resulting from tax positions taken during a prior period	—			(7,025		)	(3,285		)
Increases resulting from tax positions taken during the current period	3,169			1,656			817
Decreases related to settlements with taxing authorities	(601		)	(3,594		)	(123		)
Reductions related to the lapse of statute of limitations	(86,138		)	(19,492		)	(2,831		)
Unrecognized tax benefits at end of year	$	52,159		$	131,608		$	152,581