Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets:
Publicly traded equity securities	$ 2,647	$ 1,717
Derivative instruments	142,251	73,074
Total financial assets	1,564,218	683,780
Liabilities:
Derivative instruments	2,036	9,740
Cash [Member]
Assets:
Cash and cash equivalents	832,235	486,648
Money market and deposit accounts [Member]
Assets:
Cash and cash equivalents	570,165	119,518
Certificates of deposit [Member]
Assets:
Cash and cash equivalents	16,920	2,823
Fair value, inputs, Level 1 [Member]
Assets:
Publicly traded equity securities	2,647	1,717
Derivative instruments	0	0
Total financial assets	1,405,047	607,883
Liabilities:
Derivative instruments	0	0
Fair value, inputs, Level 1 [Member] | Cash [Member]
Assets:
Cash and cash equivalents	832,235	486,648
Fair value, inputs, Level 1 [Member] | Money market and deposit accounts [Member]
Assets:
Cash and cash equivalents	570,165	119,518
Fair value, inputs, Level 1 [Member] | Certificates of deposit [Member]
Assets:
Cash and cash equivalents	0	0
Fair value, inputs, Level 2 [Member]
Assets:
Publicly traded equity securities	0	0
Derivative instruments	142,251	73,074
Total financial assets	159,171	75,897
Liabilities:
Derivative instruments	2,036	9,740
Fair value, inputs, Level 2 [Member] | Cash [Member]
Assets:
Cash and cash equivalents	0	0
Fair value, inputs, Level 2 [Member] | Money market and deposit accounts [Member]
Assets:
Cash and cash equivalents	0	0
Fair value, inputs, Level 2 [Member] | Certificates of deposit [Member]
Assets:
Cash and cash equivalents	$ 16,920	$ 2,823