Balance Sheet Accounts and Supplemental Disclosures

a. Marketable Securities

As of December 31, 2017, the Company's short-term available-for-sale investments were as follows:



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
	(In millions)
Commercial paper	$	135.6	$	—	$	—	$	135.6
U.S. treasury notes	4.1		—		—		4.1
Marketable securities	$	139.7	$	—	$	—	$	139.7

As of December 31, 2017, of the total estimated fair value, $119.7 million was classified as cash and cash equivalents as the remaining maturity at date of purchase was less than three months, and $20.0 million was classified as marketable securities. At December 31, 2017, the contractual maturities of the Company’s available-for-sale marketable securities were less than one year.

b. Accounts Receivable



	As of December 31,
	2017			2016
	(In millions)
Billed	$	62.1		$	55.7
Unbilled	195.5			124.1
Reserve for overhead rate disallowance	(42.8		)	(44.5		)
Total receivables under long-term contracts	214.8			135.3
Other receivables	0.7			1.1
Accounts receivable	$	215.5		$	136.4

The gross unbilled receivable amounts as of December 31, 2017 expected to be collected after one year are $113.7 million.

c. Inventories



	As of December 31,
	2017			2016
	(In millions)
Long-term contracts at average cost	$	562.3		$	551.9
Progress payments	(427.1		)	(368.2		)
Total long-term contract inventories	135.2			183.7
Total other inventories	1.2			1.4
Inventories	$	136.4		$	185.1

Long-term contract inventories included an allocation of general and administrative costs incurred throughout fiscal 2017 and 2016 amounting to $238.4 million and $257.4 million, respectively, and the cumulative amount of general and administrative costs in long-term contract inventories is estimated to be $11.4 million and $21.1 million as of December 31, 2017 and 2016, respectively.

d. Other Current Assets, net



	As of December 31,
	2017		2016
	(In millions)
Recoverable from the U.S. government for acquisition integration costs	$	10.9	$	11.9
Recoverable from the U.S. government and other third parties for environmental remediation costs	25.6		25.2
Receivable from Northrop for environmental remediation costs	6.0		6.0
Prepaid expenses	19.2		16.5
Cost-share and other receivables, net	7.5		17.8
Recoverable from the U.S. government for competitive improvement program obligations	14.9		7.6
Income tax receivable	20.5		26.8
Other	5.2		11.1
Other current assets, net	$	109.8	$	122.9

e. Property, Plant and Equipment, net



	As of December 31,
	2017			2016
	(In millions)
Land	$	71.2		$	71.4
Buildings and improvements	368.3			345.1
Machinery and equipment	493.2			499.9
Construction-in-progress	30.3			30.4
	963.0			946.8
Less: accumulated depreciation	(604.0		)	(580.8		)
Property, plant and equipment, net	$	359.0		$	366.0

Depreciation expense for fiscal 2017, 2016, 2015, and one month ended December 31, 2015 was $56.7 million, $49.6 million, $49.8 million, and $3.8 million, respectively. The Company had $2.9 million of non-cash property, plant and equipment additions as of December 31, 2017.

f. Goodwill.

The goodwill balance as of December 31, 2017 and 2016 relates to the Company’s Aerospace and Defense segment. The change of $3.2 million in the carrying amount of goodwill since December 31, 2015 was due to the Coleman Aerospace acquisition in fiscal 2017 (see Note 4).

g. Intangible Assets



	As of December 31, 2017
	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
	(In millions)
Customer related	$	87.2	$	46.9	$	40.3
Intellectual property\trade secrets	34.2		11.8		22.4
Trade name	21.0		3.1		17.9
Acquired technology	19.2		14.3		4.9
Intangible assets	$	161.6	$	76.1	$	85.5



	As of December 31, 2016
	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
	(In millions)
Customer related	$	83.8	$	37.4	$	46.4
Intellectual property\trade secrets	34.2		9.2		25.0
Non-compete agreements	0.5		0.5		—
Trade name	20.5		2.4		18.1
Acquired technology	18.3		13.4		4.9
Intangible assets	$	157.3	$	62.9	$	94.4

Amortization expense related to intangible assets was $13.7 million, $13.3 million, $13.4 million, and $1.1 million in fiscal 2017, 2016, 2015, and one month ended December 31, 2015, respectively.

Future amortization expense for the five succeeding years is estimated to be as follows:



Year Ending December 31,	Future Amortization Expense
	(In millions)
2018	$	13.7
2019	13.6
2020	13.4
2021	9.9
2022	6.6
	$	57.2

h. Other Noncurrent Assets, net



	As of December 31,
	2017		2016
	(In millions)
Real estate held for entitlement and leasing	$	94.0	$	91.8
Receivable from Northrop for environmental remediation costs	58.5		62.0
Recoverable from the U.S. government for acquisition integration costs	—		10.9
Recoverable from the U.S. government for conditional asset retirement obligations	22.7		20.3
Recoverable from the U.S. government for competitive improvement program obligations	18.4		1.3
Recoverable from the U.S. government for restructuring costs	25.5		12.8
Grantor trust	24.2		16.6
Note receivable, net	9.0		9.0
Income tax receivable	—		10.8
Other	7.0		8.5
Other noncurrent assets, net	$	259.3	$	244.0

i. Other Current Liabilities



	As of December 31,
	2017		2016
	(In millions)
Accrued compensation and employee benefits	$	113.4	$	105.7
Contract related liabilities	41.7		24.7
Income taxes	0.8		2.1
Competitive improvement program obligations	15.0		7.6
Postretirement medical and life insurance benefits	4.8		5.2
Interest payable	0.6		4.1
Contract loss provisions	3.8		6.8
Other	15.8		16.8
Other current liabilities	$	195.9	$	173.0

j. Other Noncurrent Liabilities



	As of December 31,
	2017		2016
	(In millions)
Conditional asset retirement obligations	$	44.0	$	30.6
Pension benefits, non-qualified	17.6		17.5
Deferred compensation	29.4		19.8
Deferred revenue	12.7		13.3
Postretirement medical and life insurance benefits	32.7		37.4
Competitive improvement program obligations	18.4		1.3
Uncertain income tax positions	2.8		28.4
Other	13.5		13.1
Other noncurrent liabilities	$	171.1	$	161.4

k. Accumulated Other Comprehensive Loss, Net of Income Taxes

Changes in accumulated other comprehensive loss by components, net of income taxes:



	Actuarial Losses, Net			Prior Service Credits, Net			Total
	(In millions)
November 30, 2015	$	(342.6	)	$	0.9		$	(341.7	)
Actuarial losses arising during the period, net of income taxes	(8.6		)	—			(8.6		)
Amortization of actuarial losses and prior service credits, net of income taxes	3.4			(0.1		)	3.3
December 31, 2015	(347.8		)	0.8			(347.0		)
Actuarial gains arising during the period, net of income taxes	7.5			—			7.5
Amortization of actuarial losses and prior service credits, net of income taxes	37.1			(0.6		)	36.5
December 31, 2016	(303.2		)	0.2			(303.0		)
Actuarial losses arising during the period, net of income taxes	(8.5		)	—			(8.5		)
Amortization of actuarial losses and prior service credits, net of income taxes	39.0			(0.1		)	38.9
December 31, 2017	$	(272.7	)	$	0.1		$	(272.6	)

The estimated amounts that will be amortized from accumulated other comprehensive loss into net periodic benefit expense in fiscal 2018:



	Pension Benefits		Medical and Life Insurance Benefits
	(In millions)
Actuarial losses (gains), net	$	70.7	$	(3.7	)
Prior service costs (credits), net	0.1		(0.2		)
	$	70.8	$	(3.9	)

l. Redeemable Common Stock

The Company inadvertently failed to register with the Securities Exchange Commission ("SEC") the issuance of certain of its common shares in its defined contribution 401(k) employee benefit plan (the “Plan”). As a result, certain Plan participants who purchased such securities pursuant to the Plan may have had the right to rescind certain of their purchases for consideration equal to the purchase price paid for the securities (or if such security has been sold, to receive consideration with respect to any loss incurred on such sale) plus interest from the date of purchase. In June 2008, the Company filed a registration statement on Form S-8 to register future transactions in the Company's stock fund in the Plan.

On May 30, 2017, the Company made a registered rescission offer to buy back unregistered shares from eligible Plan participants at the original purchase price plus interest, or to reimburse eligible Plan participants for losses they may have incurred if their shares had been sold. The registered rescission offer expired on June 30, 2017, and settlement payments of $3.5 million under the offer were completed in the third quarter of fiscal 2017 (see Note 13).