Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Assets:
Publicly traded equity securities	$ 2,215	$ 1,717
Derivative instruments	62,999	73,074
Total financial assets	1,693,747	683,780
Liabilities:
Derivative instruments	26,128	9,740
Cash [Member]
Assets:
Cash and cash equivalents	1,039,871	486,648
Money market and deposit accounts [Member]
Assets:
Cash and cash equivalents	573,658	119,518
Certificates of deposit [Member]
Assets:
Cash and cash equivalents	15,004	2,823
Fair value, inputs, Level 1 [Member]
Assets:
Publicly traded equity securities	2,215	1,717
Derivative instruments	0	0
Total financial assets	1,615,744	607,883
Liabilities:
Derivative instruments	0	0
Fair value, inputs, Level 1 [Member] | Cash [Member]
Assets:
Cash and cash equivalents	1,039,871	486,648
Fair value, inputs, Level 1 [Member] | Money market and deposit accounts [Member]
Assets:
Cash and cash equivalents	573,658	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	62,999	73,074
Total financial assets	78,003	75,897
Liabilities:
Derivative instruments	26,128	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	$ 15,004	$ 2,823