Financial Instruments and Fair Value Measurement (Tables)

3 Months Ended

Dec. 31, 2016

Financial Instruments and Fair Value Measurement

Summary of available-for-sale securities

			Gross		Gross		Estimated
			Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
	(in thousands)
Equity securities December 31, 2016	$	38,473	$	53,294	$	—	$	91,767
Equity securities September 30, 2016	$	38,473	$	33,051	$	—	$	71,524

Summary of assets measured at fair value

	Total		Level 1		Level 2		Level 3
	(in thousands)
Recurring fair value measurements:
Short-term investments:
Corporate debt securities	$	25,392	$	—	$	25,392	$	—
U.S. government and federal agency securities	19,871		15,883		3,988		—
Total short-term investments	45,263		15,883		29,380		—
Cash and cash equivalents	825,893		825,893		—		—
Investments	91,767		91,767		—		—
Other current assets	28,361		28,111		250		—
Other assets	2,000		2,000		—		—
Total assets measured at fair value	$	993,284	$	963,654	$	29,630	$	—
Nonrecurring fair value measurements:
Assets:
Assets held for sale (1)	$	1,106	$	—	$	—	$	1,106

(1) Represents the book value as of December 31, 2016 of decommissioned rigs and rig related equipment written down to their estimated recoverable amounts at December 31, 2016.  These assets are included in assets held for sale in our Consolidated Condensed BalanceSheets.

Summary of supplemental fair value information about long-term fixed-rate debt

	December 31,		September 30,
	2016		2016
	(in millions)
Carrying value of long-term fixed-rate debt	$	492.1	$	491.8
Fair value of long-term fixed-rate debt	$	513.1	$	529.6