Summary of Significant Accounting Policies - Impact of Adoption of ASU2016-02 (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease assets	$ 679,412
Total assets	32,284,116		$ 30,587,012
Other accrued expenses	1,016,087		802,388
Operating lease liabilities	455,917
Long-term deferred revenue and other long-term liabilities	461,284		470,932
Total liabilities	22,448,909		21,532,755
Total stockholders' equity (deficit)	9,330,511	$ 8,951,217	8,594,189	$ 7,806,127	$ 7,325,263	$ 6,937,906
Total liabilities and stockholders' equity (deficit)	32,284,116		$ 30,587,012
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease assets	679,412
Total assets	32,284,116
Other accrued expenses	1,016,087
Operating lease liabilities	455,917
Long-term deferred revenue and other long-term liabilities	461,284
Total liabilities	22,448,909
Total stockholders' equity (deficit)	9,330,511
Total liabilities and stockholders' equity (deficit)	32,284,116
Accounting Standards Update 2016-02 [Member] | As would have been reported under previous standards
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets	31,604,704
Other accrued expenses	792,106
Long-term deferred revenue and other long-term liabilities	461,770
Total liabilities	21,769,497
Total stockholders' equity (deficit)	9,330,511
Total liabilities and stockholders' equity (deficit)	31,604,704
Accounting Standards Update 2016-02 [Member] | Impact of adopting ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease assets	679,412
Total assets	679,412
Other accrued expenses	223,981
Operating lease liabilities	455,917
Long-term deferred revenue and other long-term liabilities	(486)
Total liabilities	679,412
Total liabilities and stockholders' equity (deficit)	$ 679,412