Restatement - Balance Sheets (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2015		Oct. 04, 2015	Jul. 05, 2015	Jul. 03, 2015	Mar. 31, 2015		Dec. 28, 2014	Sep. 28, 2014	Jun. 29, 2014	Mar. 31, 2014		Mar. 31, 2013
Current assets:
Cash and cash equivalents	$ 104,032	[1],[2]	$ 65,087	$ 49,595	$ 49,595	$ 139,253	[1],[2]	$ 112,920	$ 42,668	$ 132,739	$ 266,632	[2]	$ 417,288	[2]
Net receivables	1,670,821	[1]	1,789,963		1,774,715	1,696,529	[1]	1,255,374	1,216,362	1,240,892
Net inventories	213,212	[1]	175,317		182,276	196,114	[1]	134,241	130,962	148,056
Income taxes receivable	50,769	[1]			19	31,415	[1]	37,388	0
Deferred income taxes	0	[1]	211,687		211,695	211,721	[1]	175,763	210,465	168,644
Other current assets	89,645	[1]	126,815		128,310	118,491	[1]	71,414	39,284	47,323
Current assets held for sale								832,311	898,640	879,439
Total current assets	2,128,479	[1]	2,368,869		2,346,610	2,393,523	[1]	2,619,411	2,538,381	2,617,093
Net property, plant, and equipment	761,694	[1]	750,080		758,820	769,050	[1]	479,005	478,909	480,782
Goodwill	1,828,366	[1]	1,862,255		1,862,255	1,862,255	[1]	1,039,763	1,039,763	1,039,763	1,039,763
Net intangibles	147,156	[1]	139,284		152,184	165,207	[1]	8,148	8,922	9,695
Deferred income taxes	318,538	[1]	127,520		143,262	145,036	[1]	77,313	85,971	85,311
Other noncurrent assets	139,462	[1]	131,354		135,678	142,461	[1]	108,954	110,075	109,543
Noncurrent assets of discontinued operations								1,491,312	1,612,176	1,631,911
Total assets	5,323,695	[1]	5,379,362		5,398,809	5,477,532	[1]	5,823,906	5,874,197	5,974,098	3,490,706
Current liabilities:
Current portion of long-term debt	40,000	[1]	40,000		59,997	59,997	[1]	159,997	159,997	247,666
Accounts payable	130,812	[1]	227,051		168,827	158,137	[1]	218,321	185,779	185,930
Contract-related liabilities	381,712	[1]	276,441		312,145	358,518	[1]			0
Contract advances and allowances	172,046	[1]	154,845		178,182	173,198	[1]	142,742	118,600	120,032
Contract loss reserve	235,841	[1]	242,744		253,410	262,324	[1]	279,874	302,716	321,807
Accrued compensation	127,928	[1]	143,450		102,108	144,185	[1]	78,965	66,096	70,076
Accrued income taxes								0	14,996	35,425
Other current liabilities	166,096	[1]	167,458		186,373	220,749	[1]	181,880	182,619	174,829
Current liabilities of discontinued operations								277,977	274,512	272,835
Total current liabilities	1,254,435	[1]	1,251,989		1,261,042	1,377,108	[1]	1,339,756	1,305,315	1,428,600
Long-term debt	1,435,836	[1]	1,481,746		1,497,958	1,511,936	[1]	1,887,109	1,901,421	1,820,653
Noncurrent deferred income tax liabilities								0	0
Postretirement and postemployment benefits	59,202	[1]	70,342		72,353	74,658	[1]	64,657	66,117	69,194
Pension	761,632	[1]	811,459		845,562	851,001	[1]	439,469	490,664	518,744
Other noncurrent liabilities	127,152	[1]	131,151		130,332	141,433	[1]	101,906	100,538	101,379
Noncurrent liabilities of discontinued operations								196,050	255,689	259,926
Total liabilities	3,638,257	[1]	3,746,687		3,807,247	3,956,136	[1]	4,028,947	4,119,744	4,198,496
Commitments and contingencies (Notes 11, 13 and 14)		[1]					[1]
Common stock—$.01 par value: authorized—180,000,000 shares	587	[1]	589		593	594	[1]	319	319	319
Additional paid-in-capital	2,187,940	[1]	2,181,288		2,187,768	2,182,814	[1]	435,746	431,967	540,080
Retained earnings	1,043,043	[1]	1,010,527		951,825	894,008	[1]	2,730,772	2,698,127	2,616,557
Accumulated other comprehensive loss	(785,908)	[1]	(813,594)		(829,045)	(847,648)	[1]	(652,900)	(656,538)	(662,219)	(680,809)
Common stock in treasury, at cost	(771,029)	[1]	(757,061)		(730,358)	(719,034)	[1]	(729,832)	(730,135)	(729,767)
Total Orbital ATK, Inc. stockholders' equity	1,674,633	[1]	1,621,749		1,580,783	1,510,734	[1]	1,784,105	1,743,740	1,764,970
Noncontrolling interest	10,805	[1]	10,926		10,779	10,662	[1]	10,854	10,713	10,632
Total equity	1,685,438	[1],[3]	1,632,675		1,591,562	1,521,396	[1]	1,794,959	1,754,453	1,775,602	1,676,888	[3]	1,491,192	[3]
Total liabilities and equity	$ 5,323,695	[1]	$ 5,379,362		$ 5,398,809	$ 5,477,532	[1]	$ 5,823,906	$ 5,874,197	5,974,098
Common stock, par value (in dollars per share)	$ 0.01		$ 0.01		$ 0.01	$ 0.01		$ 0.01	$ 0.01
Common stock, authorized shares	180,000,000		180,000,000		180,000,000	180,000,000		180,000,000	180,000,000
Common stock, issued shares	58,729,995		58,898,248		59,274,189	59,427,942		31,938,188	31,931,354
Common stock, outstanding shares	58,729,995		58,898,248		59,274,189	59,427,942		31,938,188	31,931,354
Common stock in treasury, shares	10,205,029		10,036,776		9,660,835	9,507,082		9,638,009	9,644,843
As Reported
Current assets:
Cash and cash equivalents	$ 104,032		$ 65,087	49,595	$ 49,595	$ 139,253		$ 112,920	$ 42,668	132,739	266,632		417,288
Net receivables	1,784,434		1,882,675		1,891,338	1,793,556		1,352,062	1,288,281	1,290,540
Net inventories	211,712		175,317		182,276	196,114		134,241	130,962	148,056
Income taxes receivable	50,769				0	31,415		37,388	0
Deferred income taxes			107,466		107,466	107,484		48,999	83,701	41,880
Other current assets	89,495		129,427		130,922	121,084		71,531	39,401	47,440
Current assets held for sale								832,311	898,640	879,439
Total current assets	2,240,442		2,359,972		2,361,597	2,388,906		2,589,452	2,483,653	2,540,094
Net property, plant, and equipment	806,187		797,524		802,134	807,057		508,583	506,083	505,947
Goodwill	1,832,066		1,875,269		1,875,269	1,875,269		1,043,463	1,043,463	1,043,463
Net intangibles	147,156		139,284		152,184	165,207		8,148	8,922	9,695
Deferred income taxes	209,861		121,319		129,220	140,321		70,611	79,269	78,609
Other noncurrent assets	103,680		102,026		106,962	111,074		86,756	89,420	90,750
Noncurrent assets of discontinued operations								1,491,312	1,612,176	1,631,911
Total assets	5,339,392		5,395,394		5,427,366	5,487,834		5,798,325	5,822,986	5,900,469
Current liabilities:
Current portion of long-term debt	40,000		40,000		59,997	59,997		159,997	159,997	247,666
Accounts payable	129,312		227,051		168,827	158,137		218,321	185,779	185,930
Contract-related liabilities	340,888		268,129		314,642	357,296				0
Contract advances and allowances	172,046		154,845		178,182	173,198		142,742	118,600	120,032
Contract loss reserve	0		0		0	0		0	0	0
Accrued compensation	125,278		140,800		99,458	135,528		78,965	66,096	70,076
Accrued income taxes								0	14,996	35,425
Other current liabilities	159,455		144,192		167,847	212,628		181,880	182,619	174,829
Current liabilities of discontinued operations								277,977	274,512	272,835
Total current liabilities	966,979		975,017		988,953	1,096,784		1,059,882	1,002,599	1,106,793
Long-term debt	1,435,836		1,481,746		1,497,958	1,511,936		1,887,109	1,901,421	1,820,653
Noncurrent deferred income tax liabilities								0	0
Postretirement and postemployment benefits	59,202		70,342		72,353	74,658		64,657	66,117	69,194
Pension	761,632		811,459		845,562	851,001		439,469	490,664	518,744
Other noncurrent liabilities	167,798		150,619		149,797	165,795		102,011	100,637	101,471
Noncurrent liabilities of discontinued operations								196,050	255,689	259,926
Total liabilities	3,391,447		3,489,183		3,554,623	3,700,174		3,749,178	3,817,127	3,876,781
Commitments and contingencies (Notes 11, 13 and 14)
Common stock—$.01 par value: authorized—180,000,000 shares	587		589		593	594		319	319	319
Additional paid-in-capital	2,187,940		2,181,288		2,187,768	2,182,814		435,746	431,967	540,080
Retained earnings	1,305,550		1,284,063		1,233,006	1,160,272		2,984,960	2,949,533	2,864,643
Accumulated other comprehensive loss	(785,908)		(813,594)		(829,045)	(847,648)		(652,900)	(656,538)	(662,219)
Common stock in treasury, at cost	(771,029)		(757,061)		(730,358)	(719,034)		(729,832)	(730,135)	(729,767)
Total Orbital ATK, Inc. stockholders' equity	1,937,140		1,895,285		1,861,964	1,776,998		2,038,293	1,995,146	2,013,056
Noncontrolling interest	10,805		10,926		10,779	10,662		10,854	10,713	10,632
Total equity	1,947,945		1,906,211		1,872,743	1,787,660		2,049,147	2,005,859	2,023,688
Total liabilities and equity	5,339,392		5,395,394		5,427,366	5,487,834		5,798,325	5,822,986	5,900,469
Adjustments
Current assets:
Cash and cash equivalents	0		0	0		0		0	0	0	$ 0		$ 0
Net receivables	(113,613)					(97,027)		(96,688)	(71,919)	(49,648)
Net inventories	1,500					0		0	0	0
Income taxes receivable	0					0		0	0
Deferred income taxes						104,237		126,764	126,764	126,764
Other current assets	150					(2,593)		(117)	(117)	(117)
Current assets held for sale								0	0	0
Total current assets	(111,963)					4,617		29,959	54,728	76,999
Net property, plant, and equipment	(44,493)					(38,007)		(29,578)	(27,174)	(25,165)
Goodwill	(3,700)					(13,014)		(3,700)	(3,700)	(3,700)
Net intangibles	0					0		0	0	0
Deferred income taxes	108,677					4,715		6,702	6,702	6,702
Other noncurrent assets	35,782					31,387		22,198	20,655	18,793
Noncurrent assets of discontinued operations								0	0	0
Total assets	(15,697)					(10,302)		25,581	51,211	73,629
Current liabilities:
Current portion of long-term debt	0					0		0	0	0
Accounts payable	1,500					0		0	0	0
Contract-related liabilities	40,824					1,222				0
Contract advances and allowances	0					0		0	0	0
Contract loss reserve	235,841					262,324		279,874	302,716	321,807
Accrued compensation	2,650					8,657		0	0	0
Accrued income taxes								0	0	0
Other current liabilities	6,641					8,121		0	0	0
Current liabilities of discontinued operations								0	0	0
Total current liabilities	287,456					280,324		279,874	302,716	321,807
Long-term debt	0					0		0	0	0
Noncurrent deferred income tax liabilities								0	0
Postretirement and postemployment benefits	0					0		0	0	0
Pension	0					0		0	0	0
Other noncurrent liabilities	(40,646)					(24,362)		(105)	(99)	(92)
Noncurrent liabilities of discontinued operations								0	0	0
Total liabilities	246,810					255,962		279,769	302,617	321,715
Commitments and contingencies (Notes 11, 13 and 14)
Common stock—$.01 par value: authorized—180,000,000 shares	0					0		0	0	0
Additional paid-in-capital	0					0		0	0	0
Retained earnings	(262,507)					(266,264)		(254,188)	(251,406)	(248,086)
Accumulated other comprehensive loss	0					0		0	0	0
Common stock in treasury, at cost	0					0		0	0	0
Total Orbital ATK, Inc. stockholders' equity	(262,507)					(266,264)		(254,188)	(251,406)	(248,086)
Noncontrolling interest	0					0		0	0	0
Total equity	(262,507)					(266,264)		(254,188)	(251,406)	(248,086)
Total liabilities and equity	(15,697)		(13,925)			(10,302)		25,581	51,211	73,629
First Restatement Adjustments | Adjustments
Current assets:
Cash and cash equivalents			0		0
Net receivables			15,986		(13,719)
Net inventories			0		0
Income taxes receivable					0
Deferred income taxes			0		0
Other current assets			0		0
Total current assets			15,986		(13,719)
Net property, plant, and equipment			(4,200)		(2,100)
Goodwill			(9,314)		(9,314)
Net intangibles			0		0
Deferred income taxes			(4,579)		3,286
Other noncurrent assets			0		0
Total assets			(2,107)		(21,847)
Current liabilities:
Current portion of long-term debt			0		0
Accounts payable			0		0
Contract-related liabilities			(13,274)		(27,783)
Contract advances and allowances			0		0
Contract loss reserve			0		0
Accrued compensation			0		0
Other current liabilities			15,875		15,616
Total current liabilities			2,601		(12,167)
Long-term debt			0
Postretirement and postemployment benefits			0		0
Pension			0		0
Other noncurrent liabilities			6,254		9,955
Total liabilities			8,855		(2,212)
Commitments and contingencies (Notes 11, 13 and 14)
Common stock—$.01 par value: authorized—180,000,000 shares			0		0
Additional paid-in-capital			0		0
Retained earnings			(10,962)		(19,635)
Accumulated other comprehensive loss			0		0
Common stock in treasury, at cost			0		0
Total Orbital ATK, Inc. stockholders' equity			(10,962)		(19,635)
Noncontrolling interest			0		0
Total equity			(10,962)		(19,635)
Total liabilities and equity			(2,107)		(21,847)
Second Restatement Adjustments | Adjustments
Current assets:
Cash and cash equivalents			0		0
Net receivables			(108,698)		(102,904)
Net inventories			0		0
Income taxes receivable					19
Deferred income taxes			104,221		104,229
Other current assets			(2,612)		(2,612)
Total current assets			(7,089)		(1,268)
Net property, plant, and equipment			(43,244)		(41,214)
Goodwill			(3,700)		(3,700)
Net intangibles			0		0
Deferred income taxes			10,780		10,756
Other noncurrent assets			29,328		28,716
Total assets			(13,925)		(6,710)
Current liabilities:
Current portion of long-term debt			0		0
Accounts payable			0		0
Contract-related liabilities			21,586		25,286
Contract advances and allowances			0		0
Contract loss reserve			242,744		253,410
Accrued compensation			2,650		2,650
Other current liabilities			7,391		2,910
Total current liabilities			274,371		284,256
Long-term debt			0		0
Postretirement and postemployment benefits			0		0
Pension			0		0
Other noncurrent liabilities			(25,722)		(29,420)
Total liabilities			248,649		254,836
Common stock—$.01 par value: authorized—180,000,000 shares			0		0
Additional paid-in-capital			0		0
Retained earnings			(262,574)		(261,546)
Accumulated other comprehensive loss			0		0
Common stock in treasury, at cost			0		0
Total Orbital ATK, Inc. stockholders' equity			(262,574)		(261,546)
Noncontrolling interest			0		0
Total equity			(262,574)		(261,546)
Total liabilities and equity					$ (6,710)
Long-term debt | Accounting Standards Update 2015-03
Current liabilities:
Deferred issuance costs	14,000		15,000	16,000		17,000		21,000	22,000	23,000
Other noncurrent assets | Accounting Standards Update 2015-03
Current liabilities:
Deferred issuance costs	$ (14,000)		$ 0	$ 0		$ (17,000)		$ 0	$ 0	$ 0

[1] See Note 2 - Restatement

[2] See Note 2 - Restatement

[3] See Note 2 - Restatement