Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes [Line Items]
Provisional deferred tax benefit due to tax cuts and jobs act of 2017		$ 158,286	$ 0	$ 0
Provisional transition tax obligation for repatriation of foreign earnings		144,167	0	0
Initial income tax benefit due to tax cuts and jobs act of 2017		14,000
Reduction in current income tax payable attributable to stock-based compensation		100,000	76,000	$ 130,000
Valuation allowance		(76,280)	$ (65,516)
Decrease in NOL valuation allowance		10,000
Effective interest rate of federal statutory income tax rate			35.00%	35.00%
Unrecognized tax benefits		260,919	$ 220,532	$ 171,177	$ 110,561
Unrecognized tax benefits that would impact effective tax rate		155,000	181,000
Uncertain tax positions, interest and penalties		22,000	15,000
Interest and penalties		7,000	$ 5,000	$ 3,000
Federal
Income Taxes [Line Items]
Net operating loss carryforwards		65,000
State
Income Taxes [Line Items]
Net operating loss carryforwards		210,000
Foreign
Income Taxes [Line Items]
Net operating loss carryforwards		370,000
Indefinite foreign net operating loss carryforwards		253,000
Foreign net operating loss carryforwards subject to expiration		$ 117,000
IRS
Income Taxes [Line Items]
Increase in prior years taxable revenue due to tax examination	$ 105,000
Additional federal tax expense due to tax examination	$ 37,000