CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		126 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018
Cash Flows From Operating Activities:
Net income (loss)	$ 287,542	$ (93,457)	$ 491,350	$ 147,501
Adjustments to reconcile net income (loss) to net cash flows from operating activities:
Depreciation and amortization	160,233	191,314	338,752	373,342
Realized and unrealized losses (gains) on investments			17,443	(1,803)
Non-cash, stock-based compensation			18,705	11,863
Deferred tax expense (benefit)			(12,703)	(22,854)
Other, net			(66,827)	12,797
Changes in current assets and current liabilities, net			(126,440)	194,876
Net cash flows from operating activities			660,280	715,722
Cash Flows From Investing Activities:
(Purchases) Sales and maturities of marketable investment securities, net			98,085	247
Purchases of property and equipment			(157,593)	(210,030)
Purchases of strategic investments				(90,381)	$ (21,000,000)
Other, net			5,543	7,044
Net cash flows from investing activities			(53,965)	(293,120)
Cash Flows From Financing Activities:
Redemption and repurchases of senior notes			(1,088,392)
Payments made to parent of transferred businesses				(7,098)
Advances from affiliates			155,283
Repayment of long-term debt and capital lease obligations			(18,569)	(19,052)
Other, net			(2,760)
Net cash flows from financing activities			(954,438)	(26,150)
Net increase (decrease) in cash, cash equivalents, restricted cash and cash equivalents			(348,123)	396,452
Cash, cash equivalents, restricted cash and cash equivalents, beginning of period (Note 4)			365,066	778,259
Cash, cash equivalents, restricted cash and cash equivalents, end of period (Note 4)	$ 16,943	$ 1,174,711	$ 16,943	$ 1,174,711	$ 16,943