Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2018

Equity [Abstract]

Stock Option Activity Under Equity-Based Plans

The following table summarizes stock option activity under our 2009 Plan for the three months ended March 31, 2018:

	Number of Shares
Balance at December 31, 2017	1,296,863
Exercised	(206,430	)
Forfeited	(4,167	)
Balance at March 31, 2018	1,086,266
Exercisable at March 31, 2018	1,011,038

Restricted Stock Unit and Restricted Stock Award Activity Under Equity-Based Plans

The following tables summarize restricted stock unit (RSU), performance-based restricted stock unit (PSU), RSA, and PRSA activity under our 2009 Plan for the three months ended March 31, 2018:

	RSUs				PSUs
	Number of Units		Weighted-Average Grant Date Fair Value		Number of Units		Weighted-Average Grant Date Fair Value
Nonvested at December 31, 2017	2,249,661		$	24.83	453,674		$	30.72
Granted	548,054		46.97		23,842		47.61
Vested	(286,121	)	23.96		(82,066	)	33.51
Forfeited	(88,396	)	25.51		—		—
Nonvested at March 31, 2018	2,423,198		$	29.91	395,450		$	30.89

	RSAs			PRSAs
	Number of Units	Weighted-Average Grant Date Fair Value		Number of Units	Weighted-Average Grant Date Fair Value
Nonvested at December 31, 2017	—	$	—	—	$	—
Granted	72,991	47.61		169,088	47.61
Nonvested at March 31, 2018	72,991	$	47.61	169,088	$	47.61

Performance Stock Unit and Performance Stock Award Activity Under Equity-Based Plans

The following tables summarize restricted stock unit (RSU), performance-based restricted stock unit (PSU), RSA, and PRSA activity under our 2009 Plan for the three months ended March 31, 2018:

	RSUs				PSUs
	Number of Units		Weighted-Average Grant Date Fair Value		Number of Units		Weighted-Average Grant Date Fair Value
Nonvested at December 31, 2017	2,249,661		$	24.83	453,674		$	30.72
Granted	548,054		46.97		23,842		47.61
Vested	(286,121	)	23.96		(82,066	)	33.51
Forfeited	(88,396	)	25.51		—		—
Nonvested at March 31, 2018	2,423,198		$	29.91	395,450		$	30.89

	RSAs			PRSAs
	Number of Units	Weighted-Average Grant Date Fair Value		Number of Units	Weighted-Average Grant Date Fair Value
Nonvested at December 31, 2017	—	$	—	—	$	—
Granted	72,991	47.61		169,088	47.61
Nonvested at March 31, 2018	72,991	$	47.61	169,088	$	47.61

Stock-based Compensation Expense

Stock-based compensation expense and other disclosures for stock-based awards made to our employees pursuant to the equity plans was as follows: 

	Three Months Ended March 31,
(in millions)	2018		2017
Cost of providing services	$	2	$	2
Sales and marketing	2		1
General and administrative	4		2
Systems development and programming costs	1		1
Total stock-based compensation expense	$	9	$	6
Income tax benefit related to stock-based compensation expense	$	2	$	2
Tax benefit realized from stock options exercised and similar awards	$	6	$	6