Stock Based Awards and Other Equity Instruments (Tables)

6 Months Ended

Jun. 30, 2016

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Amount of Stock-Based Compensation Expense Related to Stock-Based Awards

The following table presents the amount of stock-based compensation expense related to stock-based awards on our unaudited condensed consolidated statements of operations during the periods presented:

	Three months ended						Six months ended
	June 30,						June 30,
	2016			2015			2016			2015
	(in millions)						(in millions)
Selling and marketing	$	5		$	4		$	10		$	8
Technology and content		10			7			20			13
General and administrative		7			7			12			13
Total stock-based compensation		22			18			42			34
Income tax benefit from stock-based compensation		(8	)		(6	)		(15	)		(12	)
Total stock-based compensation, net of tax effect	$	14		$	12		$	27		$	22

Summary of Stock Option

A summary of the status and activity for stock option awards relating to our common stock for the six months ended June 30, 2016, is presented below:

				Weighted		Weighted
				Average		Average
				Exercise		Remaining		Aggregate
	Options			Price Per		Contractual		Intrinsic
	Outstanding			Share		Life		Value
	(in thousands)					(in years)		(in millions)
Options outstanding at January 1, 2016		5,720		$	53.71
Granted		1,033			63.44
Exercised (1)		(554	)		29.34
Cancelled or expired		(165	)		69.53
Options outstanding at June 30, 2016		6,034		$	57.18		5.9	$	78
Exercisable as of June 30, 2016		2,874		$	42.45		4.6	$	71
Vested and expected to vest after June 30, 2016		5,647		$	56.59		5.7	$	77

(1) Inclusive of 246,826 options which were not converted into shares due to net share settlement in order to cover the aggregate exercise price and the minimum amount of required employee withholding taxes. Potential shares that had been convertible under stock options that were withheld under net share settlement remain in the authorized but unissued pool under the 2011 Plan and can be reissued by the Company. Total payments for the employees’ tax obligations to the taxing authorities due to net share settlements are reflected as a financing activity within the unaudited condensed consolidated statements of cash flows.

Weighted-Average Assumptions of Estimated Fair Value of Stock Option Grants

The fair value of stock option grants under the 2011 Plan has been estimated at the date of grant using the Black–Scholes option pricing model with the following weighted average assumptions for the periods presented:

	Three months ended						Six months ended
	June 30,						June 30,
	2016			2015			2016			2015
Risk free interest rate		1.08	%		1.55	%		1.20	%		1.52	%
Expected term (in years)		4.31			5.24			4.84			5.21
Expected volatility		42.09	%		40.66	%		41.82	%		41.83	%
Expected dividend yield	—  %			—  %			—  %			—  %

Summary of RSU Activity

The following table presents a summary of our RSU activity during the six months ended June 30, 2016:

				Weighted
				Average
				Grant-		Aggregate
	RSUs			Date Fair		Intrinsic
	Outstanding			Value Per Share		Value
	(in thousands)					(in millions)
Unvested RSUs outstanding as of January 1, 2016		1,750		$	79.02
Granted		1,731			63.95
Vested and released (1)		(409	)		72.57
Cancelled		(141	)		74.69
Unvested RSUs outstanding as of June 30, 2016		2,931		$	71.21	$	186
Expected to vest after June 30, 2016		2,517		$	71.48	$	160

(1) Inclusive of 121,869 RSUs withheld to satisfy employee minimum tax withholding requirements due to net share settlement. Potential shares which had been convertible under RSUs that were withheld under net share settlement remain in the authorized but unissued pool under the 2011 Plan and can be reissued by the Company. Total payments for the employees’ tax obligations to the taxing authorities due to net share settlements are reflected as a financing activity within the unaudited condensed consolidated statements of cash flows.

Summary of Unrecognized Stock-Based Compensation Expense, Net of Estimated Forfeitures and Weighted Average Period Remaining

A summary of our remaining unrecognized stock-based compensation expense, net of estimated forfeitures, and the weighted average remaining amortization period at June 30, 2016 related to our non-vested stock options and RSU awards is presented below (in millions, except per year information):

	Stock
	Options		RSUs
Unrecognized compensation expense (net of estimated forfeitures)	$	60	$	150
Weighted average period remaining (in years)		2.6		3.0