Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

Reconciliations of Statutory U.S. Federal Income Tax Rates to Our Effective Tax Rate for Continuing Operations

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

	Years Ended December 31,
	2014		2013		2012
Statutory rate	35.0	%	35.0	%	35.0	%
State tax, net of federal benefit	2.9		2.6		—
Effect of state rate change on net deferred tax liabilities, net of federal benefit	4.4		—		(0.1	)
State, release valuation allowance on net operating losses	(4.0	)	—		—
Unrecognized tax benefits, U.S. federal and state, net of federal benefit	4.8		—		—
Other, net	(1.2	)	0.6		2.0
Effective tax rate	41.9	%	38.2	%	36.9	%

Components of Provision for Income Tax Expense (Benefit)

Income tax expense consists of:

	December 31,
	2014			2013		2012
Current provision:
Federal	$	137,573		$	130,854	$	126,484
State	43,282			13,513		10,674
Total current provision	180,855			144,367		137,158
Deferred (benefit)/provision:
Federal	(40,370		)	13,240		(9,747		)
State	(518		)	1,327		(1,268		)
Total deferred (benefit)/provision	(40,888		)	14,567		(11,015		)
Provision for income tax expense	$	139,967		$	158,934	$	126,143

Schedule of Deferred Tax Assets and Liabilities

The tax effect of temporary differences that give rise to deferred tax assets and liabilities include the following:

	December 31,
	2014			2013
Deferred tax assets:
Loan reserves	$	33,570		$	26,853
Stock-based compensation plans	16,342			28,211
Deferred revenue	418			607
Operating loss and credit carryovers	14,324			1,273
Unrealized losses	7,185			1,849
Accrued expenses not currently deductible	10,606			2,853
Unrecorded tax benefits	19,798			2,331
Other	8,918			334
Total deferred tax assets	111,161			64,311
Deferred tax liabilities:
Gains on repurchased debt	251,671			—
Fixed assets	5,849			3,181
Acquired intangible assets	6,151			616
Student loan premiums and discounts, net	3,050			(87		)
Other	2,656			3
Total deferred tax liabilities	269,377			3,713
Net deferred tax (liabilities) assets	$	(158,216	)	$	60,598

Summary of Changes in Unrecognized Tax Benefits

The following table summarizes changes in unrecognized tax benefits:

	December 31,
	2014			2013		2012
Unrecognized tax benefits at beginning of year	$	7,343.5		$	3,951.1	$	2,467.3
Increases resulting from tax positions taken during a prior period	45,184.2			573.9		503.1
Increases resulting from tax positions taken during the current period	7,712.5			2,818.5		980.7
Decreases related to settlements with taxing authorities	(235.7		)	—		—
Reductions related to the lapse of statute of limitations	(599.6		)	—		—
Unrecognized tax benefits at end of year	$	59,404.9		$	7,343.5	$	3,951.1