Parsons (PSN) 10-Q 4 Nov 20 2020 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Oct. 28, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Trading Symbol	PSN
Entity Registrant Name	Parsons Corporation
Entity Central Index Key	0000275880
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		100,727,119
Entity File Number	001-07782
Entity Tax Identification Number	95-3232481
Entity Address, Address Line One	5875 Trinity Parkway #300
Entity Address, City or Town	Centreville
Entity Address, State or Province	VA
Entity Address, Postal Zip Code	20120
City Area Code	703
Local Phone Number	988-8500
Title of 12(b) Security	Common Stock, $1 par value
Security Exchange Name	NYSE
Document Quarterly Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	DE
Entity Interactive Data Current	Yes

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents (including $50,585 and $51,171 Cash of consolidated joint ventures)	$ 614,031	$ 182,688
Restricted cash and investments	3,726	12,686
Accounts receivable, net (including $259,691 and $166,355 Accounts receivable of consolidated joint ventures, net)	775,060	671,492
Contract assets (including $29,054 and $26,458 Contract assets of consolidated joint ventures)	610,893	575,089
Prepaid expenses and other current assets (including $3,974 and $11,182 Prepaid expenses and other current assets of consolidated joint ventures)	77,909	84,454
Total current assets	2,081,619	1,526,409
Property and equipment, net (including $2,649 and $2,945 Property and equipment of consolidated joint ventures, net)	121,486	122,751
Right of use assets, operating leases	212,592	233,415
Goodwill	1,046,453	1,047,425
Investments in and advances to unconsolidated joint ventures	71,289	68,620
Intangible assets, net	194,082	259,858
Deferred tax assets	130,904	130,401
Other noncurrent assets	60,336	61,489
Total assets	3,918,761	3,450,368
Current liabilities:
Accounts payable (including $72,949 and $85,869 Accounts payable of consolidated joint ventures)	208,307	216,613
Accrued expenses and other current liabilities (including $141,476 and $74,857 Accrued expenses and other current liabilities of consolidated joint ventures)	725,867	639,863
Contract liabilities (including $44,267 and $32,638 Contract liabilities of consolidated joint ventures)	212,373	230,681
Short-term lease liabilities, operating leases	48,661	49,994
Income taxes payable	1,342	7,231
Short-term debt	50,000	0
Total current liabilities	1,246,550	1,144,382
Long-term employee incentives	21,535	56,928
Long-term debt	537,119	249,353
Long-term lease liabilities, operating leases	189,319	203,624
Deferred tax liabilities	9,273	9,621
Other long-term liabilities	145,494	125,704
Total liabilities	2,149,290	1,789,612
Contingencies (Note 12)
Shareholders' equity (deficit):
Common stock, $1 par value; authorized 1,000,000,000 shares; 146,498,582 and 146,440,701 shares issued; 24,637,043 and 21,772,888 public shares outstanding; 76,090,531 and 78,896,806 ESOP shares outstanding	146,498	146,441
Treasury stock, 45,771,008 shares at cost	(934,240)	(934,240)
Additional paid-in capital	2,675,383	2,649,975
Accumulated deficit	(142,095)	(218,025)
Accumulated other comprehensive loss	(18,049)	(14,261)
Total Parsons Corporation shareholders' equity	1,727,497	1,629,890
Noncontrolling interests	41,974	30,866
Total shareholders' equity	1,769,471	1,660,756
Total liabilities, redeemable common stock and shareholders' equity	$ 3,918,761	$ 3,450,368

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Cash and cash equivalents	$ 614,031	$ 182,688
Accounts receivable, net	775,060	671,492
Contract assets	610,893	575,089
Prepaid expenses and other current assets	77,909	84,454
Property and equipment, net	121,486	122,751
Accounts payable	208,307	216,613
Accrued expenses and other current liabilities	725,867	639,863
Contract liabilities	$ 212,373	$ 230,681
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares, issued	146,498,582	146,440,701
Common stock, shares, outstanding	24,637,043	21,772,888
Treasury stock, shares	45,771,008	45,771,008
ESOP
Common stock, shares, outstanding	76,090,531	78,896,806
Consolidated Joint Ventures
Cash and cash equivalents	$ 50,585	$ 51,171
Accounts receivable, net	259,691	166,355
Contract assets	29,054	26,458
Prepaid expenses and other current assets	3,974	11,182
Property and equipment, net	2,649	2,945
Accounts payable	72,949	85,869
Accrued expenses and other current liabilities	141,476	74,857
Contract liabilities	$ 44,267	$ 32,638

Consolidated Statements of Inco

Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Revenue	$ 1,004,236	$ 1,023,277	$ 2,954,688	$ 2,917,424
Direct cost of contracts	788,769	798,552	2,307,725	2,297,512
Equity in earnings of unconsolidated joint ventures	16,741	7,274	26,624	29,305
Indirect, general and administrative expenses	165,937	178,550	537,351	581,428
Operating income	66,271	53,449	136,236	67,789
Interest income	88	427	512	1,129
Interest expense	(5,475)	(4,909)	(13,656)	(19,577)
Other income (expense), net	1,653	(3,127)	1,916	(1,580)
Total other income (expense)	(3,734)	(7,609)	(11,228)	(20,028)
Income before income tax expense	62,537	45,840	125,008	47,761
Income tax (expense) benefit	(16,017)	15,453	(32,992)	67,063
Net income including noncontrolling interests	46,520	61,293	92,016	114,824
Net income attributable to noncontrolling interests	(5,862)	(4,481)	(15,086)	(8,012)
Net income attributable to Parsons Corporation	$ 40,658	$ 56,812	$ 76,930	$ 106,812
Earnings per share:
Basic	$ 0.40	$ 0.57	$ 0.76	$ 1.19
Diluted	$ 0.40	$ 0.57	$ 0.76	$ 1.19

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income including noncontrolling interests	$ 46,520	$ 61,293	$ 92,016	$ 114,824
Other comprehensive income (loss), net of tax
Foreign currency translation adjustment, net of tax	1,926	171	(3,770)	4,958
Pension adjustments, net of tax	20	(9)	(18)	17
Comprehensive income including noncontrolling interests, net of tax	48,466	61,455	88,228	119,799
Comprehensive income attributable to noncontrolling interests, net of tax	(5,866)	(4,481)	(15,086)	(8,012)
Comprehensive income attributable to Parsons Corporation, net of tax	$ 42,600	$ 56,974	$ 73,142	$ 111,787

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net income including noncontrolling interests	$ 92,016	$ 114,824
Adjustments to reconcile net income to net cash used in operating activities
Depreciation and amortization	95,442	92,692
Amortization of debt issue costs	760	802
Amortization of convertible notes discount	1,277	0
Gain on disposal of property and equipment	(22)	1,045
Provision for doubtful accounts	54	(964)
Deferred taxes	(763)	(105,161)
Foreign currency transaction gains and losses	431	1,689
Equity in earnings of unconsolidated joint ventures	(26,624)	(29,305)
Return on investments in unconsolidated joint ventures	31,189	32,848
Stock-based compensation	11,044	9,224
Contributions of treasury stock	42,006	36,779
Changes in assets and liabilities, net of acquisitions and newly consolidated joint ventures:
Accounts receivable	(106,487)	(31,726)
Contract assets	(34,931)	(59,161)
Prepaid expenses and current assets	7,649	2,980
Accounts payable	(8,074)	(6,946)
Accrued expenses and other current liabilities	48,901	40,186
Contract liabilities	(18,094)	20,703
Income taxes	(6,761)	(3,019)
Other long-term liabilities	(15,574)	13,138
Net cash provided by operating activities	113,439	130,628
Cash flows from investing activities:
Capital expenditures	(29,178)	(44,030)
Proceeds from sale of property and equipment	1,053	2,824
Payments for acquisitions, net of cash acquired	0	(495,690)
Investments in unconsolidated joint ventures	(7,969)	(11,446)
Return of investments in unconsolidated joint ventures	17	6,632
Net cash used in investing activities	(36,077)	(541,710)
Cash flows from financing activities:
Proceeds from borrowings under credit agreement	212,900	530,000
Repayments of borrowings under credit agreement	(212,900)	(710,000)
Payments for debt costs and credit agreement	0	(286)
Proceeds from issuance of convertible notes	400,000	0
Payments for purchase of bond hedges	(54,968)	0
Proceeds from issuance of warrants	13,808	0
Transaction costs paid in connection with convertible notes issuance	(10,307)	0
Contributions by noncontrolling interests	491	8,999
Distributions to noncontrolling interests	(4,469)	(35,378)
Purchase of treasury stock	0	(819)
Taxes paid on vested stock	(1,149)	0
Proceeds from issuance of common stock	1,684	536,879
Dividend paid	0	(52,093)
Net cash provided by financing activities	345,090	277,302
Effect of exchange rate changes	(69)	(953)
Net increase (decrease) in cash, cash equivalents, and restricted cash	422,383	(134,733)
Cash, cash equivalents and restricted cash:
Beginning of year	195,374	281,195
End of period	$ 617,757	$ 146,462

Consolidated Statements of Shar

Consolidated Statements of Shareholder's Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Revision of Prior Period, Accounting Standards Update, Adjustment	Redeemable Common Stock	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings (Accumulated Deficit)	Retained Earnings (Accumulated Deficit)Revision of Prior Period, Accounting Standards Update, Adjustment	Accumulated Other Comprehensive Income (Loss)	Total Parsons Equity (Deficit)	Total Parsons Equity (Deficit)Revision of Prior Period, Accounting Standards Update, Adjustment	Noncontrolling Interest
Beginning balance at Dec. 31, 2018	$ (921,076)				$ (957,025)		$ 12,445		$ (22,957)	$ (967,537)		$ 46,461
Beginning balance (ASC 842) at Dec. 31, 2018		$ 52,608						$ 52,608			$ 52,608
Beginning balance, Temporary Equity at Dec. 31, 2018			$ 1,876,309
Comprehensive income
Net income	114,824						106,812			106,812		8,012
Foreign currency translation gain (loss), net	4,958								4,958	4,958
Pension adjustments, net	17								17	17
Purchase of treasury stock					(819)		819
Temporary equity, Purchase of treasury stock			(819)
Contributions	8,999											8,999
Distributions	(35,378)											(35,378)
Dividend paid	(52,093)						(52,093)			(52,093)
Issuance of equity securities, net of retirements/ IPO proceeds, net	536,878			$ 21,296		$ 515,582				536,878
Stock-based compensation	9,224					9,224				9,224
Conversion of S-Corp to C-Corp	(25,877)						(25,877)			(25,877)
Temporary equity, Conversion of S-Corp to C-Corp			25,877
ESOP shares at redemption value	(675,644)					(516,034)	(159,610)			(675,644)
Temporary equity, ESOP shares at redemption value			675,644
Ending Balance at Sep. 30, 2019	(982,560)			21,296	(957,844)	8,772	(64,896)		(17,982)	(1,010,654)		28,094
Ending Balance, Temporary Equity at Sep. 30, 2019			2,577,011
Beginning balance at Jun. 30, 2019	(1,342,226)			21,296	(957,844)		(424,886)		(18,144)	(1,379,578)		37,352
Beginning balance, Temporary Equity at Jun. 30, 2019			2,880,189
Comprehensive income
Net income	61,293						56,812			56,812		4,481
Foreign currency translation gain (loss), net	171								171	171
Pension adjustments, net	(9)								(9)	(9)
Contributions	852											852
Distributions	(14,591)											(14,591)
Issuance of equity securities, net of retirements/ IPO proceeds, net	(452)					(452)				(452)
Stock-based compensation	9,224					9,224				9,224
ESOP shares at redemption value	303,178						303,178			303,178
Temporary equity, ESOP shares at redemption value			(303,178)
Ending Balance at Sep. 30, 2019	(982,560)			21,296	(957,844)	8,772	(64,896)		(17,982)	(1,010,654)		28,094
Ending Balance, Temporary Equity at Sep. 30, 2019			$ 2,577,011
Beginning balance at Dec. 31, 2019	1,660,756			146,441	(934,240)	2,649,975	(218,025)		(14,261)	1,629,890		30,866
Beginning balance (ASC 2016-13) at Dec. 31, 2019		$ (1,000)						$ (1,000)			$ (1,000)
Comprehensive income
Net income	92,016						76,930			76,930		15,086
Foreign currency translation gain (loss), net	(3,770)								(3,770)	(3,770)
Pension adjustments, net	(18)								(18)	(18)
Contributions	491											491
Distributions	(4,469)											(4,469)
Issuance of equity securities, net of retirements/ IPO proceeds, net	1,672			57		1,615				1,672
Equity component value of convertible note issuance	53,552					53,552				53,552
Purchase of convertible note hedge	(54,611)					(54,611)				(54,611)
Sale of common stock warrants	13,808					13,808				13,808
Stock-based compensation	11,044					11,044				11,044
Ending Balance at Sep. 30, 2020	1,769,471			146,498	(934,240)	2,675,383	(142,095)		(18,049)	1,727,497		41,974
Beginning balance at Jun. 30, 2020	1,706,252			146,496	(934,240)	2,658,036	(182,753)		(19,991)	1,667,548		38,704
Comprehensive income
Net income	46,520						40,658			40,658		5,862
Foreign currency translation gain (loss), net	1,926								1,922	1,922		4
Pension adjustments, net	20								20	20
Contributions	268											268
Distributions	(2,864)											(2,864)
Issuance of equity securities, net of retirements/ IPO proceeds, net	(12)			2		(14)				(12)
Equity component value of convertible note issuance	53,552					53,552				53,552
Purchase of convertible note hedge	(54,611)					(54,611)				(54,611)
Sale of common stock warrants	13,808					13,808				13,808
Stock-based compensation	4,612					4,612				4,612
Ending Balance at Sep. 30, 2020	$ 1,769,471			$ 146,498	$ (934,240)	$ 2,675,383	$ (142,095)		$ (18,049)	$ 1,727,497		$ 41,974

Description of Operations

Description of Operations	9 Months Ended
	Sep. 30, 2020
Description Of Operations Disclosure [Abstract]
Description of Operations	1. Description of Operations Organization Parsons Corporation, a Delaware corporation, and its subsidiaries (collectively, the “Company”) is a leading provider of technology-driven solutions in the defense, intelligence and critical infrastructure markets. We provide software and hardware products, technical services and integrated solutions to support our customers’ missions. We have developed significant expertise and differentiated capabilities in key areas of cybersecurity, intelligence, missile defense, C5ISR, space, geospatial, and connected communities. By combining our talented team of professionals and advanced technology, we help solve complex technical challenges to enable a safer, smarter and more interconnected world. Initial Public Offering On May 8, 2019, the Company consummated its initial public offering (“IPO”) whereby the Company sold 18,518,500 shares of common stock for $27.00 per share. The underwriters exercised their option on May 14, 2019 to purchase an additional 2,777,775 shares at the net price of $25.515 which was the IPO share price of $27.00 less the underwriting discount of $1.485 per share. The net proceeds of the IPO and the underwriters’ option were $536.9 million, after deducting underwriting discounts and other fees, and were used to fund an IPO dividend of $52.1 million, repay the outstanding balance of $150.0 million under our Term Loan, and repay outstanding indebtedness under our Revolving Credit Facility. Stock Dividend On April 15, 2019, the board of directors of the Company declared a common stock dividend in a ratio of two shares of common stock for every one share of common stock presently held by the Company’s stockholder (the “Stock Dividend”). The record date of this common Stock Dividend was May 7, 2019, the day immediately prior to the consummation of the Company’s IPO on May 8, 2019, and the payment date of the Stock Dividend was May 8, 2019. Purchasers of the Company’s common stock in the Company’s public offering were not entitled to receive any portion of the Stock Dividend.

Basis of Presentation and Princ

Basis of Presentation and Principles of Consolidation	9 Months Ended
	Sep. 30, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation and Principles of Consolidation	2 . The accompanying unaudited consolidated financial statements and related notes of the Company have been prepared in accordance with generally accepted accounting principles in the United States of America ("GAAP") and pursuant to the interim period reporting requirements of Form 10-Q. They do not include all of the information and footnotes required by GAAP for complete financial statements and, therefore, should be read in conjunction with our consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. In the opinion of management, the consolidated financial statements reflect all normal recurring adjustments necessary for a fair statement of the financial position, results of operations and cash flows for the interim periods presented. The results of operations and cash flows for any interim period are not necessarily indicative of results for the full year or for future years. This Quarterly Report on Form 10-Q includes the accounts of Parsons Corporation and its subsidiaries and affiliates which it controls. Interests in joint ventures that are controlled by the Company, or for which the Company is otherwise deemed to be the primary beneficiary, are consolidated. For joint ventures in which the Company does not have a controlling interest, but exerts a significant influence, the Company applies the equity method of accounting. (see “Note 14 – Use of Estimates The preparation of the consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual amounts could differ from those estimates. The Company’s most significant estimates and judgments involve revenue recognition with respect to the determination of the costs to complete contracts and transaction price; determination of self-insurance reserves; useful lives of property and equipment and intangible assets; calculation of allowance for doubtful accounts; valuation of deferred income tax assets and uncertain tax positions, among others. Please see “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Critical Accounting Policies and Estimates” and “Note 2—Summary of Significant Accounting Polices” in the notes to our consolidated financial statements included in the Company’s Form 10-K for the year ended December 31, 2019, for a discussion of the significant estimates and assumptions affecting our consolidated financial statements. Estimates of costs to complete contracts are continually evaluated as work progresses and are revised when necessary. When a change in estimate is determined to have an impact on contract profit, the Company records a positive or negative adjustment to the consolidated statement of income. Employee Stock Purchase Plan During the second quarter of fiscal 2020, initial purchases of the Company’s common Stock were made under the Parsons Employee Stock Purchase Program (“ESPP”). Under the ESPP, eligible employees who elect to participate are granted the right to purchase shares of the common stock of Parsons at a discount that is limited to 5% of the per-share market value on the day shares are sold to employees. Purchases of common stock under the ESPP are included in “proceeds from issuance of common stock” in cash flows from financing activities in the Consolidated Statements of Cash Flows.

New Accounting Pronouncements

New Accounting Pronouncements	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
New Accounting Pronouncements	3 . In the first quarter of 2020, the Company adopted Accounting Standards Update (“ASU”) 2016-13, “Measurement of Credit Losses on Financial Instruments.” The amendments in ASU 2016-13 replace the incurred loss impairment methodology in current practice with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to estimate credit losses. The adoption of ASU 2016-13 did not have a material impact on the Company’s consolidated financial statements. In December 2019, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”). ASU 2019-12 was issued as a means to reduce the complexity of accounting for income taxes for those entities that fall within the scope of the standard. The guidance is to be applied using a prospective method, excluding amendments related to franchise taxes, which should be applied on either a retrospective basis for all periods presented or a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year of adoption. ASU 2019-12 is effective for fiscal years beginning after December 15, 2020, with early adoption permitted. The Company does not expect this standard to have a material impact on its consolidated financial statements. In August 2020, the FASB issued ASU 2020-06, Debt – Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging – Contracts in Entity’s Own Equity (Subtopic 815-40). The update simplifies the accounting for convertible debt instruments and convertible preferred stock by reducing the number of accounting models and limiting the number of embedded conversion features separately recognized from the primary contract. The guidance also includes targeted improvements to the disclosures for convertible instruments and earnings per share. ASU 2020-06 is effective for fiscal years beginning after December 15, 2021, including interim periods within those fiscal years. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020. The Company expects to early adopt this standard using the modified retrospective method. The Company is evaluating the impact of the adoption on its consolidated financial statements, and expects it will result in a reduction in non-cash interest expense and a reclassification of the equity portion of the Convertible Senior Notes to liabilities on the consolidated balance sheet.

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2020
Business Combinations [Abstract]
Acquisitions	4. OGSystems On January 7, 2019, the Company acquired a 100% ownership interest in OGSystems, a privately-owned company, for $292.4 million paid in cash. OGSystems provides geospatial intelligence, big data analytics and threat mitigation for defense and intelligence customers. The Company borrowed $110 million under the Credit Agreement and $150 million on a short-term loan, as described in “Note 10— Debt and Credit Facilities The following table summarizes the estimated fair values of the assets acquired and liabilities assumed based on the purchase price allocation as of the date of acquisition (in thousands): Amount Cash and cash equivalents $ 5,772 Accounts receivable 9,904 Contract assets 9,747 Prepaid expenses and other current assets 4,307 Property and equipment 4,085 Right of use assets, operating leases 8,826 Goodwill 183,540 Intangible assets 92,300 Other noncurrent assets 10 Accounts payable (5,450 ) Accrued expenses and other current liabilities (7,147 ) Contract liabilities (1,300 ) Short-term lease liabilities, operating leases (805 ) Income tax payable (1,178 ) Deferred tax liabilities (1,195 ) Long-term lease liabilities, operating leases (8,021 ) Other long-term liabilities (1,015 ) Net assets acquired $ 292,380 Of the total purchase price, the following values were assigned to intangible assets (in thousands, except for years): Gross Carrying Amount Amortization Period (in years) Customer relationships $ 57,100 5 Backlog 27,700 3 Trade name 3,800 2 Non-compete agreements 2,400 3 Developed technologies $ 1,300 3 Amortization expense of The amount of revenue generated by OGSystems and included within consolidated revenues is $46.2 million and $33.7 million for the three months September 30, 2020 and September 30, 2019, respectively, and $117.0 million and $ 108.7 million for the nine months ended September 30, 2020 and September 30, 2019, respectively. The Company has determined that the presentation of net income from the date of acquisition is impracticable due to the integration of general corporate functions upon acquisition. Supplemental Pro Forma Information (Unaudited) Supplemental information of unaudited pro forma operating results assuming the OGSystems acquisition had been consummated as of the beginning of fiscal year 2018 (December 30, 2017) (in thousands) is as follows: Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Pro forma revenue $ 1,004,236 $ 1,023,277 $ 2,954,688 $ 2,919,379 Pro forma net income including noncontrolling interests $ 47,561 $ 61,293 $ 95,189 $ 118,896 QRC Technologies On July 31, 2019 the Company acquired a 100% ownership interest in QRC Technologies (“QRC”), a privately-owned company, for $214.1 million in cash. QRC provides design and development of open-architecture radio-frequency products. The Company borrowed $140.0 million under the Revolving Credit Facility to partially fund the transaction. In connection with this acquisition, the Company recognized $4.9 million of acquisition-related expenses in “Indirect, general and administrative expense” in the consolidated statements of income for the fiscal year ended December 31, 2019, including legal fees, consulting fees, and other miscellaneous direct expenses associated with the acquisition. QRC is an agile, disruptive product company that specializes in radio frequency spectrum survey, record and playback; signals intelligence; and electronic warfare missions. QRC complements our existing portfolio, increases our presence in the high-growth markets of spectrum awareness and surveillance, and adds critical intellectual property that complements and expands the Company’s available capabilities for the Special Operations and Intelligence Communities. The following table summarizes the estimated fair values of the assets acquired and liabilities assumed based on the purchase price allocation as of the date of acquisition (in thousands): Amount Cash and cash equivalents $ 5,925 Accounts receivable 5,587 Prepaid expenses and other current assets 5,727 Property and equipment 1,205 Right of use assets, operating leases 5,228 Goodwill 125,091 Intangible assets 76,200 Accounts payable (1,567 ) Accrued expenses and other current liabilities (4,025 ) Short-term lease liabilities, operating leases (545 ) Long-term lease liabilities, operating leases (4,683 ) Net assets acquired $ 214,143 Of the total purchase price, the following values were assigned to intangible assets (in thousands, except for years): Gross Carrying Amount Amortization Period (in years) Customer relationships $ 49,800 12 Developed technologies 21,800 3 to 5 In-process research and development 1,800 3 to 5 Non-compete agreements 1,200 4 Trade name 800 2 Backlog 800 1 Amortization expense of $3.5 million and $1.9 million related to these intangible assets was recorded for the three months ended September 30, 2020 and September 30, 2019, respectively, and $10.6 million and $1.9 million for the nine months ended September 30, 2020 and September 30, 2019, respectively. The entire value of goodwill of $125.1 million was assigned to the Federal Solutions reporting unit and represents synergies expected to be realized from this business combination. Goodwill in its entirety is deductible for tax purposes. The amount of revenue generated by QRC and included within consolidated revenues is $12.6 million and $5.6 million for the three months ended September 30, 2020 and September 30, 2019, respectively, and $25.2 million and $5.6 million for the nine months ended September 30, 2020 and September 30, 2019, respectively. The Company has determined that the presentation of net income from the date of acquisition is impracticable due to the integration of general corporate functions upon acquisition. Supplemental Pro Forma Information Supplemental information on an unaudited pro forma basis, assuming the QRC Technologies acquisition had been consummated as of the beginning of fiscal year 2018 (December 30, 2017) (in thousands) is as follows: Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Pro forma revenue $ 1,004,236 $ 1,026,831 $ 2,954,688 $ 2,938,973 Pro forma net income including noncontrolling interests $ 47,618 $ 65,782 $ 95,994 $ 117,399

Contracts with Customers

Contracts with Customers	9 Months Ended
	Sep. 30, 2020
Revenue From Contract With Customer [Abstract]
Contracts with Customers	5 . Contracts with Customers Disaggregation of Revenue The Company’s contracts contain both fixed-price and cost reimbursable components. Contract types are based on the component that represents the majority of the contract. The following table presents revenue disaggregated by contract type (in thousands): Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Fixed-Price $ 324,901 $ 288,316 $ 944,577 $ 850,658 Time-and-Materials 265,987 285,586 777,807 810,656 Cost-Plus 413,348 449,375 1,232,304 1,256,110 Total $ 1,004,236 $ 1,023,277 $ 2,954,688 $ 2,917,424 See “Note 18 – Segments Information” for the Company’s revenues by business lines. Contract Assets a nd Contract Liabilities Contract assets and contract liabilities balances at September 30, 2020 and December 31, 2019 were as follows (in thousands): September 30, 2020 December 31, 2019 $ change % change Contract assets $ 610,893 $ 575,089 $ 35,804 6.2 % Contract liabilities 212,373 230,681 (18,308 ) -7.9 % Net contract assets (liabilities) (1) $ 398,520 $ 344,408 $ 54,112 15.7 % (1) Total contract retentions included in net contract assets (liabilities) were $89.8 million During the three months ended September 30, 2020 and September 30, 2019, the Company recognized revenue of $9.5 million and $2.1 million, respectively, and $132.2 million and $115.1 million during the nine months ended September 30, 2020 and September 30, 2019, respectively that was included in the corresponding contract liability balances at December 31, 2019 and December 31, 2018, respectively. Certain changes in contract assets and contract liabilities consisted of the following: September 30, 2020 December 31, 2019 Acquired contract assets $ - $ 9,747 Acquired contract liabilities - 1,300 Change in the estimate of variable consideration - 12,166 There was no significant impairment of contract assets recognized during the three and nine months ended September 30, 2020 and September 30, 2019. Revisions in estimates, such as changes in estimated claims or incentives, related to performance obligations partially satisfied in previous periods that individually had an impact of $5 million or more on revenue resulted in the following changes in revenue: Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Revenue impact, net $ (134 ) $ 9,116 $ 8,848 $ 9,116 Accounts Receivable, net Accounts receivable, net consisted of the following as of September 30, 2020 and December 31, 2019 (in thousands): September 30, 2020 December 31, 2019 Billed $ 527,654 $ 475,528 Unbilled 252,963 201,461 Total accounts receivable, gross 780,617 676,989 Allowance for doubtful accounts (5,557 ) (5,497 ) Total accounts receivable, net $ 775,060 $ 671,492 Billed accounts receivable represents amounts billed to clients that have not been collected. Unbilled accounts receivable represents amounts where the Company has a present contractual right to bill but an invoice has not been issued to the customer at the period-end date. In connection with the adoption of ASU 2016-13, we have modified the historical presentation of gross receivables and the allowance for doubtful accounts to reflect only expected credit losses in the allowance in conformity with the current period presentation. The allowance for doubtful accounts was determined based on consideration of trends in actual and forecasted credit quality of clients, including delinquency and payment history, type of client, such as a government agency or commercial sector client, and general economic conditions and particular industry conditions that may affect a client’s ability to pay. COVID-19 Impacts: We have not seen and do not expect there to be a risk of non-payment from either our government agency or commercial customers. We have experienced payment delays due to administrative limitations from both types of customers. Transaction Price Allocated to the Remaining Unsatisfied Performance Obligations The Company’s remaining unsatisfied performance obligations (“RUPO”) as of September 30, 2020 represent a measure of the total dollar value of work to be performed on contracts awarded and in-progress. The Company had $5.0 billion in RUPO as of September 30, 2020. RUPO will increase with awards of new contracts and decrease as the Company performs work and recognizes revenue on existing contracts. Projects are included within RUPO at such time the project is awarded and agreement on contract terms has been reached. The difference between RUPO and backlog relates to unexercised option years that are included within backlog and the value of Indefinite Delivery/Indefinite Quantity (“IDIQ”) contracts included in backlog for which delivery orders have not been issued. RUPO is comprised of: (a) original transaction price, (b) change orders for which written confirmations from our customers have been received, (c) pending change orders for which the Company expects to receive confirmations in the ordinary course of business, and (d) claim amounts that the Company has made against customers for which it has determined that it has a legal basis under existing contractual arrangements and a significant reversal of revenue is not probable, less revenue recognized to-date. The Company expects to satisfy its RUPO as of September 30, 2020 over the following periods (in thousands): Period RUPO Will Be Satisfied Within One Year Within One to Two Years Thereafter Federal Solutions $ 1,174,719 $ 379,069 $ 560,850 Critical Infrastructure 1,408,497 700,549 749,792 Total $ 2,583,216 $ 1,079,618 $ 1,310,642

Leases

Leases	9 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Leases	6. The Company has operating and finance leases for corporate and project office spaces, vehicles, heavy machinery and office equipment. Our leases have remaining lease terms of one year to 10 years, some of which may include options to extend the leases for up to five years, and some of which may include options to terminate the leases up to the third year. The components of lease costs for the three and nine months ended September 30, 2020 and September 30, 2019 are as follows (in thousands): Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Operating lease cost $ 15,919 $ 17,969 $ 48,945 $ 53,835 Short-term lease cost 4,301 5,429 12,254 10,925 Amortization of right-of-use assets 531 120 1,036 455 Interest on lease liabilities 64 15 109 46 Sublease income (959 ) (712 ) (2,771 ) (2,727 ) Total lease cost $ 19,856 $ 22,821 $ 59,573 $ 62,534 Supplemental cash flow information related to leases for the nine months ended September 30, 2020 and September 30, 2019 is as follows (in thousands): Nine Months Ended September 30, 2020 September 30, 2019 Operating cash flows for operating leases $ 45,343 $ 52,056 Operating cash flows for financing activities 111 46 Financing cash flows from finance leases 1,080 524 Right-of-use assets obtained in exchange for new operating lease liabilities 19,587 274,212 Right-of-use assets obtained in exchange for new finance lease liabilities $ - $ 1,818 Supplemental balance sheet and other information related to leases as of September 30, 2020 and December 31, 2019 are as follows (in thousands): September 30, 2020 December 31, 2019 Operating Leases: Right-of-use assets $ 212,592 $ 233,415 Lease liabilities: Current $ 48,661 $ 49,994 Long-term 189,319 203,624 Total operating lease liabilities $ 237,980 $ 253,618 Finance Leases: Other noncurrent assets $ 2,757 $ 2,377 Accrued expenses and other current liabilities $ 1,345 $ 1,075 Other long-term liabilities $ 1,247 $ 1,202 Weighted Average Remaining Lease Term: Operating leases 5 years 6 years Finance leases 2 years 3 years Weighted Average Discount Rate: Operating leases 3.8 % 4.0 % Finance leases 4.7 % 4.5 % As of September 30, 2020, the Company has no operating leases that have not yet commenced. A maturity analysis of the future undiscounted cash flows associated with the Company’s operating and finance lease liabilities as of September 30, 2020 is as follows (in thousands): Operating Leases Finance Leases 2020 (remaining) $ 11,735 $ 381 2021 58,792 1,291 2022 53,521 735 2023 46,386 316 2024 36,502 8 Thereafter 55,471 - Total lease payments 262,407 2,731 Less: imputed interest (24,427 ) (139 ) Total present value of lease liabilities $ 237,980 $ 2,592

Goodwill

Goodwill	9 Months Ended
	Sep. 30, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill	7 . The following table summarizes the changes in the carrying value of goodwill by reporting segment at September 30, 2020 and December 31, 2019 (in thousands): December 31, 2019 Foreign Exchange September 30, 2020 Federal Solutions $ 975,405 $ - $ 975,405 Critical Infrastructure 72,020 (972 ) 71,048 Total $ 1,047,425 $ (972 ) $ 1,046,453 The ultimate impact from the COVID-19 pandemic is difficult to predict. While many uncertainties exist, we currently anticipate no material change in our financial condition or results of operations. Although the Company does not anticipate a material change to our financial condition or results of operations, the Company performed a qualitative triggering analysis and determined there was no triggering event indicating a potential impairment to the carrying value of its goodwill at September 30, 2020 and concluded there has not been an impairment.

Intangible Assets

Intangible Assets	9 Months Ended
	Sep. 30, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible Assets	8. The gross amount and accumulated amortization of intangible assets with finite useful lives included in “Intangible assets, net” on the consolidated balance sheets are as follows (in thousands except for years): September 30, 2020 December 31, 2019 Weighted Average Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Amortization Period (in years) Backlog $ 109,255 $ (97,713 ) $ 11,542 $ 109,255 $ (87,510 ) $ 21,745 3 Customer relationships 228,529 (99,646 ) 128,883 228,529 (67,809 ) 160,720 7 Leases 670 (594 ) 76 670 (580 ) 90 5 Developed technology 110,939 (61,902 ) 49,037 110,939 (40,749 ) 70,190 4 Trade name 8,200 (7,392 ) 808 8,200 (5,667 ) 2,533 1 Non-compete agreements 3,600 (1,750 ) 1,850 3,600 (925 ) 2,675 3 In process research and development 1,800 - 1,800 1,800 - 1,800 n/a Other intangibles 275 (189 ) 86 275 (170 ) 105 10 Total intangible assets $ 463,268 $ (269,186 ) $ 194,082 $ 463,268 $ (203,410 ) $ 259,858 The aggregate amortization expense of intangible assets for the three months ended September 30, 2020 and September 30, 2019 was $20.9 million and $22.1 million, respectively, and for the nine months ended September 30, 2020 and September 30, 2019 was $65.7 million and $64.5 million, respectively. Estimated amortization expense for the remainder of the current fiscal year and in each of the next four years and beyond is as follows (in thousands): September 30, 2020 2020 (remaining) $ 20,820 2021 81,573 2022 36,098 2023 23,549 2024 9,098 Thereafter 21,144 Total $ 192,282

Property and Equipment, Net

Property and Equipment, Net	9 Months Ended
	Sep. 30, 2020
Property Plant And Equipment [Abstract]
Property and Equipment, Net	9 . Property and equipment consisted of the following at September 30, 2020 and December 31, 2019 (in thousands): September 30, 2020 December 31, 2019 Useful life (years) Buildings and leasehold improvements $ 93,361 $ 81,065 1-15 Furniture and equipment 92,199 91,720 3-10 Computer systems and equipment 173,606 164,161 3-10 Construction equipment 9,477 11,765 5-7 368,643 348,711 Accumulated depreciation (247,157 ) (225,960 ) Property and equipment, net $ 121,486 $ 122,751 Depreciation expense for the three months ended September 30, 2020 and September 30, 2019 was $9.5 million and $8.9 million, respectively, and $28.9 million and $28.2 million, respectively, for the nine months ended September 30, 2020 and September 30, 2019.

Debt and Credit Facilities

Debt and Credit Facilities	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Debt and Credit Facilities	1 0 . Debt consisted of the following (in thousands): September 30, 2020 December 31, 2019 Short-Term: Senior notes $ 50,000 $ - Total Short-Term 50,000 - Long-Term: Senior notes 200,000 250,000 Convertible senior notes 400,000 - Debt discount (53,692 ) - Debt issuance costs (9,189 ) (647 ) Total long-term 537,119 249,353 Total Debt $ 587,119 $ 249,353 Revolving Credit Facility In November 2017 November 2022 Term Loan In January 2019, the Company borrowed $150.0 million under our Term Loan Agreement to partially finance the OGSystems acquisition. On May 10, 2019, the Company used proceeds from its May 8, 2019 IPO to repay the $150.0 million outstanding balance under the Term Loan and this loan is now closed. Interest expense related to the Term Loan was $0 and $2.3 million for the three and nine months ended September 30, 2019, respectively. There were no amounts outstanding in fiscal 2020. Private Placement On July 1, 2014, the Company finalized a private placement whereby the Company raised an aggregate amount of $250.0 million in debt as follows (in thousands): Tranche Debt Amount Maturity Date Interest Rates Senior Note, Series A $ 50,000 July 15, 2021 4.44 % Senior Note, Series B 100,000 July 15, 2024 4.98 % Senior Note, Series C 60,000 July 15, 2026 5.13 % Senior Note, Series D 40,000 July 15, 2029 5.38 % The Company incurred $1.1 million of debt issuance costs in connection with the private placement. On August 10, 2018, the Company finalized an amended and restated intercreditor agreement related to this private placement to more closely align certain covenants and definitions with the terms under the 2017 amended and restated Credit Agreement and incurred $0.5 million of additional issuance costs. These costs are presented as a direct deduction from the debt on the face of the consolidated balance sheets. Interest expense related to the Senior Notes for both the three and nine months ended September 30, 2020 and September 30, 2019 was $3.1 million $9.3 million The Credit Agreement and private placement includes various covenants, including restrictions on indebtedness, liens, acquisitions, investments or dispositions, payment of dividends and maintenance of certain financial ratios and conditions. The Company was in compliance with these covenants at September 30, 2020 and December 31, 2019. The Company also has in place several secondary bank credit lines for issuing letters of credit, principally for foreign contracts, to support performance and completion guarantees. Letters of credit commitments outstanding under these bank lines aggregated $198.0 million and $197.3 million at September 30, 2020 and December 31, 2019, respectively. Using a discounted cash flow technique that incorporates a market interest yield curve with adjustments for duration, optionality, and risk profile, the Company estimated the fair value (Level 2) of its senior notes at September 30, 2020 approximates $277.6 million. See “Note 16 – Fair Value of Financial Instruments” for the definition of Level 2 of the fair value hierarchy. Convertible Senior Notes In August 2020, the Company issued an aggregate $400.0 million of 0.25% Convertible Senior Notes due 2025, including the exercise of a $50.0 million initial purchasers’ option. The Company received proceeds from the issuance and sale of the Convertible Senior Notes of $389.7 million, net of $10.3 million of transaction fees and other third-party offering expenses. The Convertible Senior Notes accrue interest at a rate of 0.25% per annum, payable semi-annually on February 15 and August 15 of each year beginning on February 15, 2021, and will mature on August 15, 2025, unless earlier repurchased, redeemed or converted. The Convertible Senior Notes are the Company’s senior unsecured obligations and will rank senior in right of payment to any of the Company’s indebtedness that is expressly subordinated in right of payment to the Notes; equal in right of payment to any of the Company’s unsecured indebtedness that is not so subordinated; effectively junior in right of payment to any of the Company’s secured indebtedness, to the extent of the value of the assets securing such indebtedness; and structurally junior to all indebtedness and other liabilities (including trade payables) of the Company’s subsidiaries Each $1,000 of principal of the Notes will initially be convertible into 22.2913 shares of our common stock, which is equivalent to an initial conversion price of $44.86 per share, subject to adjustment upon the occurrence of specified events. On or after March 15, 2025 until the close of business on the second scheduled trading day immediately preceding the maturity date of the Convertible Senior Notes, holders may convert all or a portion of their Convertible Senior Notes, regardless of the conditions below. Prior to the close of business on the business day immediately preceding March 15, 2025, the Notes will be convertible at the option of the holders thereof only under the following circumstances: • during any calendar quarter commencing after the calendar quarter ending on December 31, 2020, if the last reported sale price of the Company’s common stock for at least 20 trading days, whether or not consecutive, during a period of 30 consecutive trading days ending on, and including the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day; • during the five business day period after any five consecutive trading day period in which, for each trading day of that period, the trading price per $1,000 principal amount of Convertible Senior Notes for such trading day was less than 98% of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day; • if the Company calls such Convertible Senior Notes for redemption; or • upon the occurrence of specified corporate events described in the Indenture. . The Company may redeem all or any portion of the Convertible Senior Notes for cash, at its option, on or after August 21, 2023 and before the 51 st Upon the occurrence of a fundamental change prior to the maturity date of the Convertible Senior Notes, holders of the Convertible Senior Notes may require the Company to repurchase all or a portion of the Convertible Senior Notes for cash at a price equal to 100% of the principal amount of the Convertible Senior Notes to be repurchased, plus any accrued and unpaid interest to, but excluding, the fundamental change repurchase date. Upon conversion, the Company may settle the Convertible Senior Notes for cash, shares of the Company’s common stock, or a combination thereof, at the Company’s option. If the Company satisfies its conversion obligation solely in cash or through payment and delivery of a combination of cash and shares of the Company’s common stock, the amount of cash and shares of common stock due upon conversion will be based on a daily conversion value calculated on a proportionate basis for each trading day in a 50 - trading day observation period. Under GAAP, convertible debt instruments that may be settled in cash on conversion are required to be separated into liability and equity components in a manner that reflects the issuer’s non-convertible debt borrowing rate. The carrying amount of the liability component is based on the fair value of a similar instrument that does not contain an equity conversion option. The carrying amount allocated to the equity component, which is recognized as a debt discount, represents the difference between the proceeds from the issuance of the notes and the fair value of the liability component of the notes. Based on this debt to equity ratio, debt issuance costs are then allocated to the liability and equity components in a similar manner. Accordingly, at issuance the Company allocated $336.1 million to the debt liability and $53.6 million to additional paid in capital. The difference between the principal amount of the Convertible Senior Notes and the liability component, inclusive of issuance costs, represents the debt discount, which the Company amortizes to interest expense over the term of the Convertible Senior Notes using an effective interest rate of 3.25%. During the three and nine months ended September 20, 2020, the Company recognized interest expense of $1.5 million related to the amortization of debt discount and issuance costs. As of September 30, 2020, the net carrying value of the Notes was $337.6 million. A summary as of September 30, 2020 of the gross carrying amount, unamortized debt discount including debt issuance costs, and net carrying value of the liability component of the Convertible Senior Notes is as follows: September 30, 2020 Par value $ 400,000 Debt discount $ (62,376 ) Carrying amount $ 337,624 Equity component $ 53,552 Convertible Note Hedge and Warrant Transactions In connection with the sale of the Convertible Senior Notes, the Company purchased a bond hedge designed to mitigate the potential dilution from the conversion of the Convertible Senior Notes. Under the five-year The cost of the convertible note hedge was partially offset by the Company’s sale of warrants to acquire approximately 8.9 million shares of the Company’s common stock. The warrants were initially exercisable at a price of at least $66.46 per share and are subject to customary adjustments upon the occurrence of certain events, such as the payment of dividends. The Company received $13.8 million in cash proceeds from the sales of these warrants. The bond hedge and warrant transactions effectively increased the conversion price associated with the Convertible Senior Notes during the term of these transactions from 35%, or $44.86, to 100%, or $66.46, at their issuance, thereby reducing the dilutive economic effect to shareholders upon actual conversion. The bond hedges and warrants are indexed to, and potentially settled in, shares of the Company’s common stock. The net cost of $41.2 million for the purchase of the bond hedges and sale of the warrants was recorded as a reduction to additional paid-in capital in the consolidated balance sheets. At issuance, the Company recorded a deferred tax liability of $16.2 million related to the Convertible Senior Notes debt discount and a deferred tax asset of $16.5 million related to the convertible note hedge transactions. The deferred tax liability and deferred tax asset are included net in “Deferred tax assets” on the consolidated balance sheets

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	11. On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) was enacted in response to the COVID-19 pandemic. The CARES Act, among other things, permits Net Operating Loss (“NOL“) carryovers to offset 100% of taxable income for tax years beginning before 2021. In addition, the CARES Act allows NOLs incurred in 2018, 2019, and 2020 to be carried back to each of the five preceding tax years to generate a refund of previously paid income taxes. The CARES Act contains modifications on the limitation of business interest for tax years beginning in 2019 and 2020. The modifications to Section 163(j) increase the allowable business interest deduction from 30% of adjusted taxable income to 50% of adjusted taxable income. The CARES Act also accelerates the refund of alternative minimum tax (“ AMT ”) credits that were previously accumulated. The Company does not expect that the modifications on the limitation of business interest or AMT credits would have any impact to the Company. Under the NOL carryback provision, the Company carried back some of its NOLs claiming a tax refund of $ 3.9 million relating to certain amounts associated with the acquisition of OGSystems which may be subject to certain shareholders’ claims. On July 9, 2020, the U.S. Treasury Department issued final tax regulations related to the foreign-derived intangible income and global intangible low-taxed income (“GILTI”) provisions. Also, on July 20, 2020 the U.S. Treasury Department released final tax regulations permitting a taxpayer to elect to exclude from its GILTI inclusion items of income subject to a high effective rate of foreign tax. Additionally, on August 21, 2020, the U.S. Treasury Department finalized anti-abuse regulations limiting deductions of foreign-source dividends. Separately, on September 2, 2020, the U.S. Treasury Department finalized regulations on the base erosion anti-abuse tax (“BEAT”) under IRC Section 59A. The U.S. Treasury Department also finalized a second set of regulations on the allowance for the additional first-year depreciation deduction under IRC Section 168(k) on September 16, 2020, as amended by the Tax Cuts and Jobs Act (“TCJA”), for qualified property acquired and placed in service after September 27, 2017. Lastly, on September 29, 2020, the U.S. Treasury Department issued final tax regulations addressing various aspects of the foreign tax credit regime. The Company is currently assessing the impact of the new regulations to its consolidated financial statements but does not expect a material change of its income tax expense due to the new regulations. Prior to the Company’s IPO, the Company had elected to be taxed under the provisions of Subchapter “S” of the Internal Revenue Code for federal tax purposes. As a result, income had not been subject to U.S. federal income taxes or state income taxes in those states where the “S” Corporation status is recognized. Therefore, previously, no provision or liability for federal or state income tax had been provided in the consolidated financial statements except for those states where the “S” Corporation status was not recognized, or where states imposed a tax on “S” Corporations. In connection with the Company’s IPO on May 8, 2019, the “S” Corporation status was terminated, and the Company is now treated as a “C” Corporation under the Code. The termination of the “S” Corporation election has had a material impact on the Company’s results of operations, financial condition, and cash flows as reflected in the September 30, 2020 consolidated financial statements. The effective tax rate has increased, and net income has decreased as compared to the Company’s “S” Corporation tax years, since the Company is now subject to both U.S. federal and state corporate income taxes on its earnings. The Company’s effective tax rate was 25.61% and (33.71)% for the three months ended September 30, 2020 and 2019, respectively. The change in the effective tax rate was due primarily to nonrecurring tax items included in the third quarter 2019 income taxes associated with an additional $29 million tax benefit from the remeasurement of deferred taxes associated with the Company’s change in “S” Corporation to “C” Corporation status. The Company’s effective tax rate for the nine months ended September 30, 2020 and 2019 was 26.39% and (140.42)%. The change in the effective tax rate was due primarily to the nonrecurring tax items included in 2019 for the remeasurement of deferred taxes associated with the change in tax status. The difference between the effective tax rate and the statutory U.S. Federal income tax rate of 21.0% for the quarter ended September 30, 2020 primarily relates to state income taxes and a recorded valuation allowance on foreign tax credits, partially offset by benefits related to income attributable to noncontrolling interest and federal research tax credits. As of September 30, 2020, the Company’s deferred tax assets included a valuation allowance of $17.5 million primarily related to foreign net operating loss carryforwards, foreign tax credit carryforwards, and capital losses that the Company has determined are not more-likely-than-not to be realized. The factors used to assess the likelihood of realization include: the past performance of the entities, forecasts of future taxable income, future reversals of existing taxable temporary differences, and available tax planning strategies that could be implemented to realize the deferred tax assets. The ability or failure to achieve the forecasted taxable income in these entities could affect the ultimate realization of deferred tax assets. As of September 30, 2020 and December 31, 2019, the liability for income taxes associated with uncertain tax positions was $14.7 million and $15.5 million, respectively. It is reasonably possible that the Company may realize a decrease in our uncertain tax positions of approximately $1.0 million during the next 12 months as a result of concluding various tax audits and closing tax years. Although the Company believes its reserves for its tax positions are reasonable, the final outcome of tax audits could be materially different, both favorably and unfavorably. It is reasonably possible that certain audits may conclude in the next 12 months and that the unrecognized tax benefits the Company has recorded in relation to these tax years may change compared to the liabilities recorded for these periods. However, it is not currently possible to estimate the amount, if any, of such change .

Contingencies

Contingencies	9 Months Ended
	Sep. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Contingencies	1 2 . The Company is subject to certain lawsuits, claims and assessments that arise in the ordinary course of business. Additionally, the Company has been named as a defendant in lawsuits alleging personal injuries as a result of contact with asbestos products at various project sites. Management believes that any significant costs relating to these claims will be reimbursed by applicable insurance and, although there can be no assurance that these matters will be resolved favorably, management believes that the ultimate resolution of any of these claims will not have a material adverse effect on our consolidated financial position, results of operations, or cash flows. A liability is recorded when it is both probable that a loss has been incurred and the amount of loss or range of loss can be reasonably estimated. When using a range of loss estimate, the Company records the liability using the low end of the range. The Company records a corresponding receivable for costs covered under its insurance policies. Management judgment is required to determine the outcome and the estimated amount of a loss related to such matters. Management believes that there are no claims or assessments outstanding which would materially affect the consolidated results of operations or the Company’s financial position. On or about March 1, 2017, the Peninsula Corridor Joint Powers Board, or the JPB, filed a lawsuit against Parsons Transportation Group, Inc., or PTG, in the Superior Court of California, County of San Mateo, in connection with a positive train control project on which PTG was engaged prior to termination of its contract by the JPB. PTG had previously filed a lawsuit against the JPB for breach of contract and wrongful termination. The JPB seeks damages in excess of $100.0 million, which the Company is currently disputing. In addition to filing a complaint for breach of contract and wrongful termination, the Company has denied the allegations raised by the JPB and, accordingly, filed affirmative defenses. The Company is currently defending against the JPB’s claims and the parties are still engaged in discovery. The Company also has a professional liability insurance policy to the extent the JPB proves any errors or omissions occurred. At this time, the Company is unable to determine the probability of the outcome of the litigation or determine a potential range of loss, if any. The Company has also filed a third-party claim against a subcontractor for indemnification in connection with this matter. In September 2015, a former Parsons employee filed an action in the United States District Court for the Northern District of Alabama against us as a qui tam relator on behalf of the United States (the “Relator”) alleging violation of the False Claims Act. The United States government did not intervene in this matter as it is allowed to do so under the statute. The Company filed a motion to dismiss the lawsuit on the grounds that the Relator did not meet the applicable statute of limitations. The District Court granted the motion to dismiss. The Relator’s attorney appealed the decision to the United States Court of Appeals of the Eleventh Circuit, which ultimately ruled in favor of the Relator, and the Company petitioned the United States Supreme Court to review the decision. The Supreme Court reviewed the decision and accepted the position of the Relator. The case was thus remanded to the United States District Court for the Northern District of Alabama. The defendants, including Parsons, will file appropriate pleadings opposing the allegations. At this time, the Company is unable to determine the probability of the outcome of the litigation or determine a potential range of loss, if any. On or about October 4, 2019, LBH Engineers, LLC (“LBH”) filed a lawsuit against Parsons, PTG, and various other parties in the US District Court of for the Northern District of Georgia, in connection with an alleged infringement of LBH’s patent. LBH seeks damages and costs incurred by LBH, a post - judgment royalty, treble damages if the infringement is found to be willful, among other damages, which the Company and the other defendants are currently disputing. At this time, the Company is unable to determine the probability of the outcome of the litigation or determine a potential range of loss, if any. Federal government contracts are subject to audits, which are performed for the most part by the Defense Contract Audit Agency (“DCAA”). Audits by the DCAA and other agencies consist of reviews of our overhead rates, operating systems and cost proposals to ensure that we account for such costs in accordance with the Cost Accounting Standards (“CAS”). If the DCAA determines we have not accounted for such costs in accordance with the CAS, the DCAA may disallow these costs. The disallowance of such costs may result in a reduction of revenue and additional liability for the Company. Historically, the Company has not experienced any material disallowed costs as a result of government audits. However, the Company can provide no assurance that the DCAA or other government audits will not result in material disallowances for incurred costs in the future. All audits of costs incurred on work performed through 2010 have been closed, and years thereafter remain open. Although there can be no assurance that these matters will be resolved favorably, management believes that their ultimate resolution will not have a material adverse impact on the Company’s consolidated financial position, results of operations, or cash flows.

Retirement Benefit Plan

Retirement Benefit Plan	9 Months Ended
	Sep. 30, 2020
Compensation And Retirement Disclosure [Abstract]
Retirement Benefit Plan	1 3 . The Company’s principal retirement benefit plan is the Parsons Employee Stock Ownership Plan (“ESOP”), a stock bonus plan, established in 1975 to cover eligible employees of the Company and certain affiliated companies. Contributions of treasury stock to the ESOP are made annually in amounts determined by the Company’s board of directors and are held in trust for the sole benefit of the participants. Shares allocated to a participant’s account are fully vested after three years of credited service, or in the event(s) of reaching age 65, death or disability while an active employee of the Company. As of September 30, 2020 and December 31, 2019, total shares of the Company’s common stock were 100,727,574 and 100,669,694, respectively, of which 76,090,531 A participant’s interest in their ESOP account is redeemable upon certain events, including retirement, death, termination due to permanent disability, a severe financial hardship following termination of employment, certain conflicts of interest following termination of employment, or the exercise of diversification rights. Distributions from the ESOP of participants’ interests are made in the Company’s common stock based on quoted prices of a share of the Company’s common stock on the NYSE. A participant will be able to sell such shares of common stock in the market, subject to any requirements of the federal securities laws. Total ESOP contribution expense was $12.5 million and $12.3 million for the three months ended September 30, 2020 and September 30, 2019, respectively, and $42.0 million and $36.8 million for the nine months ended September 30, 2020 and September 30, 2019, respectively. On April 3, 2019, the board of directors of the Company declared a cash dividend to the Company’s sole existing shareholder at that time, the ESOP, in the amount of $2.00 per share, or $52.1 million in the aggregate (the “IPO Dividend”). The IPO Dividend was paid on May 10, 2019. On April 15, 2019, the board of directors of the Company declared a common stock dividend in a ratio of two shares of common stock for every one share of common stock then held by the Company’s shareholder (the “Stock Dividend”). The record date of the Stock Dividend was May 7, 2019, the day immediately prior to the consummation of the Company’s IPO on May 8, 2019, and the payment date of the Stock Dividend was May 8, 2019. Purchasers of the Company’s common stock in the Company’s public offering were not entitled to receive any portion of the Stock Dividend.

Investments in and Advances to

Investments in and Advances to Joint Ventures	9 Months Ended
	Sep. 30, 2020
Equity Method Investments And Joint Ventures [Abstract]
Investments in and Advances to Joint Ventures	1 4 . The Company participates in joint ventures to bid, negotiate and complete specific projects. The Company is required to consolidate these joint ventures if it holds the majority voting interest or if the Company meets the criteria under the consolidation model, as described below. The Company performs an analysis to determine whether its variable interests give the Company a controlling financial interest in a Variable Interest Entity (“VIE”) for which the Company is the primary beneficiary and should, therefore, be consolidated. Such analysis requires the Company to assess whether it has the power to direct the activities of the VIE and the obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. The Company analyzed all of its joint ventures and classified them into two groups: (1) joint ventures that must be consolidated because they are either not VIEs and the Company holds the majority voting interest, or because they are VIEs and the Company is the primary beneficiary; and (2) joint ventures that do not need to be consolidated because they are either not VIEs and the Company holds a minority voting interest, or because they are VIEs and the Company is not the primary beneficiary. Many of the Company’s joint venture agreements provide for capital calls to fund operations, as necessary; however, such funding is infrequent and is not anticipated to be material. Letters of credit outstanding described in “Note 10 – Debt and Credit Facilities” that relate to project ventures are $59.9 million In the table below, aggregated financial information relating to the Company’s joint ventures is provided because their nature, risk and reward characteristics are similar. None of the Company’s current joint ventures that meet the characteristics of a VIE are individually significant to the consolidated financial statements. Consolidated Joint Ventures The following represents financial information for consolidated joint ventures included in the consolidated financial statements (in thousands): September 30, 2020 December 31, 2019 Current assets $ 343,304 $ 255,167 Noncurrent assets 2,935 2,860 Total assets 346,239 258,027 Current liabilities 260,175 193,583 Total liabilities 260,175 193,583 Total joint venture equity $ 86,064 $ 64,444 Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Revenue $ 117,344 $ 117,611 $ 335,511 $ 341,719 Costs 105,223 108,839 304,308 322,826 Net income $ 12,121 $ 8,772 $ 31,203 $ 18,893 Net income attributable to noncontrolling interests $ 5,862 $ 4,481 $ 15,086 $ 8,012 The assets of the consolidated joint ventures are restricted for use only by the particular joint venture and are not available for the Company’s general operations. Unconsolidated Joint Ventures The Company accounts for its unconsolidated joint ventures using the equity method of accounting. Under this method, the Company recognizes its proportionate share of the net earnings of these joint ventures as “Equity in earnings (loss) of unconsolidated joint ventures” in the consolidated statements of income. The Company’s maximum exposure to loss as a result of its investments in unconsolidated VIEs is typically limited to the aggregate of the carrying value of the investment and future funding commitments. The following represents the financial information of the Company’s unconsolidated joint ventures as presented in their unaudited financial statements (in thousands): September 30, 2020 December 31, 2019 Current assets $ 792,763 $ 801,335 Noncurrent assets 567,919 564,160 Total assets 1,360,682 1,365,495 Current liabilities 753,623 655,495 Noncurrent liabilities 493,576 507,131 Total liabilities 1,247,199 1,162,626 Total joint venture equity $ 113,483 $ 202,869 Investments in and advances to unconsolidated joint ventures $ 71,289 $ 68,620 Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Revenue $ 594,640 $ 474,600 $ 1,286,087 $ 1,225,284 Costs 551,624 452,001 1,202,315 1,166,008 Net income $ 43,016 $ 22,599 $ 83,772 $ 59,276 Equity in earnings of unconsolidated joint ventures $ 16,741 $ 7,274 $ 26,624 $ 29,305 The Company received net distributions from its unconsolidated joint ventures for the three months ended September 30, 2020 and September 30, 2019 of $11.2 million and $13.7 million, respectively, and for the nine months ended September 30, 2020 and September 30, 2019 of $23.2 million

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2020
Related Party Transactions [Abstract]
Related Party Transactions	15. The Company often provides services to unconsolidated joint ventures and revenues include amounts related to recovering overhead costs for these services. Revenues related to services the Company provided to unconsolidated joint ventures for the three months ended September 30, 2020 and September 30, 2019 were $42.0 million and $28.8 million, respectively, and for the nine months ended September 30, 2020 and September 30, 2019 were $124.7 million and $113.1 million, respectively. For the three months ended September 30, 2020 and September 30, 2019, the Company incurred $32.3 million and $20.5 million, respectively, and for the nine months ended September 30, 2020 and September 30, 2019, $98.3 million and $86.3 million, respectively, of reimbursable costs. Amounts included in the consolidated balance sheets related to services the Company provided to unconsolidated joint ventures are as follows (in thousands): September 30, 2020 December 31, 2019 Accounts receivable $ 35,838 $ 37,425 Contract assets 5,703 6,955 Contract liabilities 3,352 4,509

Fair Value of Financial Instrum

Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	1 6 . The authoritative guidance on fair value measurement defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (referred to as an “exit price”). At September 30, 2020 and December 31, 2019, the Company’s financial instruments include cash, cash equivalents, accounts receivable, accounts payable, and other liabilities. The fair values of these financial instruments approximate their carrying values due to their short-term maturities. Investments measured at fair value are based on one or more of the following three valuation techniques: • Market approach —Prices and other relevant information generated by market transactions involving identical or comparable assets or liabilities; • Cost approach —Amount that would be required to replace the service capacity of an asset (i.e., replacement cost); and • Income approach —Techniques to convert future amounts to a single present amount based on market expectations (including present value techniques, option-pricing models and lattice models). In addition, the guidance establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted market prices in active markets for identical assets and liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are: Level 1 Unadjusted quoted prices in active markets that are accessible at the measurement date for identical assets and liabilities; Level 2 Pricing inputs that include quoted prices for similar assets and liabilities in active markets and inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the instrument; and Level 3 Prices or valuations that require inputs that are both significant to the fair value measurements and unobservable. The methods described above may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Furthermore, while the Company believes its valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement at the reporting date. Refer to Notes to Consolidated Financial Statements included in the Company’s Form 10-K for the year ended December 31, 2019 for a more complete discussion of the various items within the consolidated financial statements measured at fair value and the methods used to determine fair value.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Earnings Per Share	1 7 . The following tables reconcile the denominator and numerator used to compute basic earnings per share (“EPS”) to the denominator and numerator used to compute diluted EPS for the three and nine months ended September 30, 2020 and September 30, 2019. Basic EPS is computed using the weighted average number of shares outstanding during the period and income available to shareholders. Diluted EPS is computed similar to basic EPS, except the income available to shareholders is adjusted to add back interest expense, after tax related to the Convertible Senior Note, and the weighted average number of shares outstanding is adjusted to reflect the dilutive effects of equity-based awards and shares underlying the Convertible Senior Note. Dilutive potential common shares include shares the Company could be obligated to issue from its Convertible Senior Notes and warrants (see Note 10 for further discussion) and equity-based awards. Shares to be provided to the Company from its bond hedge purchased concurrently with the issuance of Convertible Senior Notes are anti-dilutive and are not included in its diluted shares. Anti-dilutive equity-based awards excluded from the calculation of earnings per share for the three and nine months ended September 30, 2020 were 205 and 3,318, respectively. The weighted average number of shares used to compute basic and diluted EPS were: Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Basic weighted average number of shares outstanding 100,736,862 99,434,877 100,700,498 89,977,493 Equity-based awards 378,486 - 321,070 - Convertible senior notes 4,458,265 - - - Diluted weighted average number of shares outstanding 105,573,613 99,434,877 101,021,568 89,977,493 The net income available to shareholders to compute basic and diluted EPS were (in thousands): Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Net income attributable to Parsons Corporation 40,658 56,812 76,930 106,812 Convertible senior notes if-converted method interest adjustment 1,164 - - - Diluted net income attributable to Parsons Corporation 41,822 56,812 76,930 106,812

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Segment Information	18. The Company operates in two reportable segments: Federal Solutions and Critical Infrastructure. The Federal Solutions segment provides advanced technical solutions to the U.S. government, delivering timely, cost-effective hardware, software and services for mission-critical projects. The segment provides advanced technologies, supporting national security missions in cybersecurity, missile defense, and military facility modernization, logistics support, hazardous material remediation and engineering services. The Critical Infrastructure segment provides integrated engineering and management services for complex physical and digital infrastructure around the globe. The Critical Infrastructure segment is a technology innovator focused on next generation digital systems and complex structures. Industry leading capabilities in engineering and project management allow the Company to deliver significant value to customers by employing cutting-edge technologies, improving timelines and reducing costs. The Company defines its reportable segments based on the way the chief operating decision maker (“CODM”), currently its Chairman and Chief Executive Officer, evaluates the performance of each segment and manages the operations of the Company for purposes of allocating resources among the segments. The CODM evaluates segment operating performance using segment Revenue and segment Adjusted EBITDA attributable to Parsons Corporation. The following table summarizes business segment revenue for the periods presented (in thousands): Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Federal Solutions revenue $ 498,156 $ 486,175 $ 1,457,937 $ 1,387,484 Critical Infrastructure revenue 506,080 537,102 1,496,751 1,529,940 Total revenue $ 1,004,236 $ 1,023,277 $ 2,954,688 $ 2,917,424 The Company defines Adjusted EBITDA attributable to Parsons Corporation as Adjusted EBITDA excluding Adjusted EBITDA attributable to noncontrolling interests. The Company defines Adjusted EBITDA as net income (loss) attributable to Parsons Corporation, adjusted to include net income (loss) attributable to noncontrolling interests and to exclude interest expense (net of interest income), provision for income taxes, depreciation and amortization and certain other items that are not considered in the evaluation of ongoing operating performance. These other items include net income (loss) attributable to noncontrolling interests, asset impairment charges, income and expense recognized on litigation matters, expenses incurred in connection with acquisitions and other non-recurring transaction costs and expenses related to our prior restructuring. The following table reconciles business segment Adjusted EBITDA attributable to Parsons Corporation to Net Income attributable to Parsons Corporation for the periods presented (in thousands): Three Months Ended Nine Months Ended Adjusted EBITDA attributable to Parsons Corporation September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Federal Solutions $ 45,874 $ 50,359 $ 125,191 $ 126,658 Critical Infrastructure 48,856 33,976 111,732 102,177 Adjusted EBITDA attributable to Parsons Corporation 94,730 84,335 236,923 228,835 Adjusted EBITDA attributable to noncontrolling interests 6,071 4,655 15,535 8,384 Depreciation and amortization (30,952 ) (31,027 ) (95,442 ) (92,692 ) Interest expense, net (5,387 ) (4,482 ) (13,144 ) (18,448 ) Income tax (expense) benefit (16,017 ) 15,453 (32,992 ) 67,063 Equity-based compensation income (expense) 991 1,657 (4,142 ) (45,504 ) Transaction-related costs (a) (2,411 ) (9,891 ) (11,937 ) (26,961 ) Restructuring expense (b) (365 ) (309 ) (1,475 ) (2,880 ) Other (c) (140 ) 902 (1,310 ) (2,973 ) Net income including noncontrolling interests 46,520 61,293 92,016 114,824 Net income attributable to noncontrolling interests 5,862 4,481 15,086 8,012 Net income attributable to Parsons Corporation $ 40,658 $ 56,812 $ 76,930 $ 106,812 (a) Reflects costs incurred in connection with acquisitions, the IPO, and other non-recurring transaction costs, primarily fees paid for professional services and employee retention. (b) Reflects costs associated with corporate restructuring initiatives. (c) Includes a combination of gain/loss related to sale of fixed assets, software implementation costs, and other individually insignificant items that are non-recurring in nature. Asset information by segment is not a key measure of performance used by the CODM. The following tables present revenues and property and equipment, net by geographic area (in thousands): Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Revenue North America $ 831,367 $ 849,839 $ 2,429,357 $ 2,400,124 Middle East 168,043 169,028 511,591 504,604 Rest of World 4,826 4,410 13,740 12,696 Total Revenue $ 1,004,236 $ 1,023,277 $ 2,954,688 $ 2,917,424 The geographic location of revenue is determined by the location of the customer. September 30, 2020 December 31, 2019 Property and Equipment, Net North America $ 116,805 $ 117,606 Middle East 4,681 5,145 Total Property and Equipment, Net $ 121,486 $ 122,751 North America includes revenue in the United States for the three months ended September 30, 2020 and September 30, 2019 of $774.0 million and $774.2 million, respectively, and for the nine months ended September 30, 2020 and September 30, 2019 of $2.2 billion and $2.2 billion, respectively. includes $ million and $ 109.9 million of property and equipment, net in the United States at September 30, 2020 and December 31, 2019, respectively. The following table presents revenues by business lines (in thousands): Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Revenue Space & Geospatial Solutions $ 68,354 $ 49,944 $ 177,609 $ 161,469 Cyber & Intelligence 110,339 91,854 312,214 244,892 Engineered Systems 164,867 180,171 504,182 493,065 Missile Defense & C5ISR 154,596 164,206 463,932 488,058 Federal Solutions revenues 498,156 486,175 1,457,937 1,387,484 Mobility Solutions 389,714 435,749 1,180,125 1,211,571 Connected Communities 116,366 101,353 316,626 318,369 Critical Infrastructure revenues 506,080 537,102 1,496,751 1,529,940 Total Revenue $ 1,004,236 $ 1,023,277 $ 2,954,688 $ 2,917,424 Effective January 1, 2020, the Company made changes to its business lines as described below. The prior year information in the table above has been reclassified to conform to the business line changes. Federal Solutions Business Line Changes As a result of the acquisitions of Polaris Alpha, OGSystems and QRC, we realigned the five business lines within our Federal Solutions segment into four business lines. We consolidated all space and geospatial programs from the former Geospatial Solutions, Defense and Cyber & Intelligence markets into a new Space & Geospatial Solutions business line to increase focus on the critical, evolving space market. This new business line better aligns capabilities and customers to drive growth and performance execution through improved agile, end-to-end solutions and dedicated customer focus. Further, we re-named our Defense business line to Missile Defense & C5ISR. We moved our Missions Solutions business line into our Missile Defense & C5ISR, Engineered Systems and Cyber & Intelligence business lines, for better customer and capability alignment. These changes were the next logical step in our acquisition integration process, to optimize performance delivery and growth. Critical Infrastructure Business Line Changes We re-aligned our Critical Infrastructure segment from three markets to two markets. Industrial is now a part of Mobility Solutions and we moved all Middle East business into Mobility Solutions as well. We believe this will drive improved synergies among like-markets and increased collaboration in areas such as program and engineering management, civil and structural and water/wastewater treatment. We also moved Aviation to Connected Communities and consolidated the civil portion of rail and transit with the systems portion of rail and transit into a consolidated sub-market within Connected Communities to focus on growth in these critical market segments. In each, we are pursuing systems, software and hardware product advanced technology opportunities.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2020
Subsequent Events [Abstract]
Subsequent Events	19. On October 29, 2020, the Company announced that it has entered into a definitive agreement to acquire Braxton Science & Technology Group, LLC (BSTG). BSTG operates at the forefront of satellite operations, ground system automation, flighty dynamics, and spacecraft and antenna simulation for the U.S. Department of Defense and Intelligence Community. The purchase price is estimated to be $300 million and the Company anticipates using all cash to fund the transaction.

Basis of Presentation and Pri_2

Basis of Presentation and Principles of Consolidation (Policies)	9 Months Ended
	Sep. 30, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation and Principles of Consolidation	The accompanying unaudited consolidated financial statements and related notes of the Company have been prepared in accordance with generally accepted accounting principles in the United States of America ("GAAP") and pursuant to the interim period reporting requirements of Form 10-Q. They do not include all of the information and footnotes required by GAAP for complete financial statements and, therefore, should be read in conjunction with our consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. In the opinion of management, the consolidated financial statements reflect all normal recurring adjustments necessary for a fair statement of the financial position, results of operations and cash flows for the interim periods presented. The results of operations and cash flows for any interim period are not necessarily indicative of results for the full year or for future years. This Quarterly Report on Form 10-Q includes the accounts of Parsons Corporation and its subsidiaries and affiliates which it controls. Interests in joint ventures that are controlled by the Company, or for which the Company is otherwise deemed to be the primary beneficiary, are consolidated. For joint ventures in which the Company does not have a controlling interest, but exerts a significant influence, the Company applies the equity method of accounting. (see “Note 14 –
Use of Estimates	Use of Estimates The preparation of the consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual amounts could differ from those estimates. The Company’s most significant estimates and judgments involve revenue recognition with respect to the determination of the costs to complete contracts and transaction price; determination of self-insurance reserves; useful lives of property and equipment and intangible assets; calculation of allowance for doubtful accounts; valuation of deferred income tax assets and uncertain tax positions, among others. Please see “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Critical Accounting Policies and Estimates” and “Note 2—Summary of Significant Accounting Polices” in the notes to our consolidated financial statements included in the Company’s Form 10-K for the year ended December 31, 2019, for a discussion of the significant estimates and assumptions affecting our consolidated financial statements. Estimates of costs to complete contracts are continually evaluated as work progresses and are revised when necessary. When a change in estimate is determined to have an impact on contract profit, the Company records a positive or negative adjustment to the consolidated statement of income.
Employee Stock Purchase Plan	Employee Stock Purchase Plan During the second quarter of fiscal 2020, initial purchases of the Company’s common Stock were made under the Parsons Employee Stock Purchase Program (“ESPP”). Under the ESPP, eligible employees who elect to participate are granted the right to purchase shares of the common stock of Parsons at a discount that is limited to 5% of the per-share market value on the day shares are sold to employees. Purchases of common stock under the ESPP are included in “proceeds from issuance of common stock” in cash flows from financing activities in the Consolidated Statements of Cash Flows.
New Accounting Pronouncements	In the first quarter of 2020, the Company adopted Accounting Standards Update (“ASU”) 2016-13, “Measurement of Credit Losses on Financial Instruments.” The amendments in ASU 2016-13 replace the incurred loss impairment methodology in current practice with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to estimate credit losses. The adoption of ASU 2016-13 did not have a material impact on the Company’s consolidated financial statements. In December 2019, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”). ASU 2019-12 was issued as a means to reduce the complexity of accounting for income taxes for those entities that fall within the scope of the standard. The guidance is to be applied using a prospective method, excluding amendments related to franchise taxes, which should be applied on either a retrospective basis for all periods presented or a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year of adoption. ASU 2019-12 is effective for fiscal years beginning after December 15, 2020, with early adoption permitted. The Company does not expect this standard to have a material impact on its consolidated financial statements. In August 2020, the FASB issued ASU 2020-06, Debt – Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging – Contracts in Entity’s Own Equity (Subtopic 815-40). The update simplifies the accounting for convertible debt instruments and convertible preferred stock by reducing the number of accounting models and limiting the number of embedded conversion features separately recognized from the primary contract. The guidance also includes targeted improvements to the disclosures for convertible instruments and earnings per share. ASU 2020-06 is effective for fiscal years beginning after December 15, 2021, including interim periods within those fiscal years. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020. The Company expects to early adopt this standard using the modified retrospective method. The Company is evaluating the impact of the adoption on its consolidated financial statements, and expects it will result in a reduction in non-cash interest expense and a reclassification of the equity portion of the Convertible Senior Notes to liabilities on the consolidated balance sheet.
Leases	Leases The Company has operating and finance leases for corporate and project office spaces, vehicles, heavy machinery and office equipment. Our leases have remaining lease terms of one year to 10 years, some of which may include options to extend the leases for up to five years, and some of which may include options to terminate the leases up to the third year.

Acquisitions (Tables)

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2020
OGSystems
Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed on Preliminary Purchase Price Allocation	The following table summarizes the estimated fair values of the assets acquired and liabilities assumed based on the purchase price allocation as of the date of acquisition (in thousands): Amount Cash and cash equivalents $ 5,772 Accounts receivable 9,904 Contract assets 9,747 Prepaid expenses and other current assets 4,307 Property and equipment 4,085 Right of use assets, operating leases 8,826 Goodwill 183,540 Intangible assets 92,300 Other noncurrent assets 10 Accounts payable (5,450 ) Accrued expenses and other current liabilities (7,147 ) Contract liabilities (1,300 ) Short-term lease liabilities, operating leases (805 ) Income tax payable (1,178 ) Deferred tax liabilities (1,195 ) Long-term lease liabilities, operating leases (8,021 ) Other long-term liabilities (1,015 ) Net assets acquired $ 292,380
Schedule of Intangible Assets Value on Purchase Price	Of the total purchase price, the following values were assigned to intangible assets (in thousands, except for years): Gross Carrying Amount Amortization Period (in years) Customer relationships $ 57,100 5 Backlog 27,700 3 Trade name 3,800 2 Non-compete agreements 2,400 3 Developed technologies $ 1,300 3
Schedule of Supplemental Pro Forma Information	Supplemental information of unaudited pro forma operating results assuming the OGSystems acquisition had been consummated as of the beginning of fiscal year 2018 (December 30, 2017) (in thousands) is as follows: Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Pro forma revenue $ 1,004,236 $ 1,023,277 $ 2,954,688 $ 2,919,379 Pro forma net income including noncontrolling interests $ 47,561 $ 61,293 $ 95,189 $ 118,896
QRC Technologies
Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed on Preliminary Purchase Price Allocation	The following table summarizes the estimated fair values of the assets acquired and liabilities assumed based on the purchase price allocation as of the date of acquisition (in thousands): Amount Cash and cash equivalents $ 5,925 Accounts receivable 5,587 Prepaid expenses and other current assets 5,727 Property and equipment 1,205 Right of use assets, operating leases 5,228 Goodwill 125,091 Intangible assets 76,200 Accounts payable (1,567 ) Accrued expenses and other current liabilities (4,025 ) Short-term lease liabilities, operating leases (545 ) Long-term lease liabilities, operating leases (4,683 ) Net assets acquired $ 214,143
Schedule of Intangible Assets Value on Purchase Price	Of the total purchase price, the following values were assigned to intangible assets (in thousands, except for years): Gross Carrying Amount Amortization Period (in years) Customer relationships $ 49,800 12 Developed technologies 21,800 3 to 5 In-process research and development 1,800 3 to 5 Non-compete agreements 1,200 4 Trade name 800 2 Backlog 800 1
Schedule of Supplemental Pro Forma Information	Supplemental information on an unaudited pro forma basis, assuming the QRC Technologies acquisition had been consummated as of the beginning of fiscal year 2018 (December 30, 2017) (in thousands) is as follows: Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Pro forma revenue $ 1,004,236 $ 1,026,831 $ 2,954,688 $ 2,938,973 Pro forma net income including noncontrolling interests $ 47,618 $ 65,782 $ 95,994 $ 117,399

Contracts with Customers (Table

Contracts with Customers (Tables)	9 Months Ended
	Sep. 30, 2020
Revenue From Contract With Customer [Abstract]
Summary of Disaggregation of Revenue	The Company’s contracts contain both fixed-price and cost reimbursable components. Contract types are based on the component that represents the majority of the contract. The following table presents revenue disaggregated by contract type (in thousands): Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Fixed-Price $ 324,901 $ 288,316 $ 944,577 $ 850,658 Time-and-Materials 265,987 285,586 777,807 810,656 Cost-Plus 413,348 449,375 1,232,304 1,256,110 Total $ 1,004,236 $ 1,023,277 $ 2,954,688 $ 2,917,424
Summary of Contract Assets and Contract Liabilities	Contract assets and contract liabilities balances at September 30, 2020 and December 31, 2019 were as follows (in thousands): September 30, 2020 December 31, 2019 $ change % change Contract assets $ 610,893 $ 575,089 $ 35,804 6.2 % Contract liabilities 212,373 230,681 (18,308 ) -7.9 % Net contract assets (liabilities) (1) $ 398,520 $ 344,408 $ 54,112 15.7 % (1) Total contract retentions included in net contract assets (liabilities) were $89.8 million
Summary of Changes in Contract Assets and Contract Liabilities	Certain changes in contract assets and contract liabilities consisted of the following: September 30, 2020 December 31, 2019 Acquired contract assets $ - $ 9,747 Acquired contract liabilities - 1,300 Change in the estimate of variable consideration - 12,166
Summary of Changes in Revenue	Revisions in estimates, such as changes in estimated claims or incentives, related to performance obligations partially satisfied in previous periods that individually had an impact of $5 million or more on revenue resulted in the following changes in revenue: Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Revenue impact, net $ (134 ) $ 9,116 $ 8,848 $ 9,116
Summary of Accounts Receivable, Net	Accounts receivable, net consisted of the following as of September 30, 2020 and December 31, 2019 (in thousands): September 30, 2020 December 31, 2019 Billed $ 527,654 $ 475,528 Unbilled 252,963 201,461 Total accounts receivable, gross 780,617 676,989 Allowance for doubtful accounts (5,557 ) (5,497 ) Total accounts receivable, net $ 775,060 $ 671,492
Summary of Remaining Unsatisfied Performance Obligations Expect to Satisfy	The Company expects to satisfy its RUPO as of September 30, 2020 over the following periods (in thousands): Period RUPO Will Be Satisfied Within One Year Within One to Two Years Thereafter Federal Solutions $ 1,174,719 $ 379,069 $ 560,850 Critical Infrastructure 1,408,497 700,549 749,792 Total $ 2,583,216 $ 1,079,618 $ 1,310,642

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Summary of Lease Costs	The components of lease costs for the three and nine months ended September 30, 2020 and September 30, 2019 are as follows (in thousands): Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Operating lease cost $ 15,919 $ 17,969 $ 48,945 $ 53,835 Short-term lease cost 4,301 5,429 12,254 10,925 Amortization of right-of-use assets 531 120 1,036 455 Interest on lease liabilities 64 15 109 46 Sublease income (959 ) (712 ) (2,771 ) (2,727 ) Total lease cost $ 19,856 $ 22,821 $ 59,573 $ 62,534
Schedule of Supplemental Cash Flow Information Related to Leases	Supplemental cash flow information related to leases for the nine months ended September 30, 2020 and September 30, 2019 is as follows (in thousands): Nine Months Ended September 30, 2020 September 30, 2019 Operating cash flows for operating leases $ 45,343 $ 52,056 Operating cash flows for financing activities 111 46 Financing cash flows from finance leases 1,080 524 Right-of-use assets obtained in exchange for new operating lease liabilities 19,587 274,212 Right-of-use assets obtained in exchange for new finance lease liabilities $ - $ 1,818
Schedule of Supplemental Balance Sheet and Other Information Related to Leases	Supplemental balance sheet and other information related to leases as of September 30, 2020 and December 31, 2019 are as follows (in thousands): September 30, 2020 December 31, 2019 Operating Leases: Right-of-use assets $ 212,592 $ 233,415 Lease liabilities: Current $ 48,661 $ 49,994 Long-term 189,319 203,624 Total operating lease liabilities $ 237,980 $ 253,618 Finance Leases: Other noncurrent assets $ 2,757 $ 2,377 Accrued expenses and other current liabilities $ 1,345 $ 1,075 Other long-term liabilities $ 1,247 $ 1,202 Weighted Average Remaining Lease Term: Operating leases 5 years 6 years Finance leases 2 years 3 years Weighted Average Discount Rate: Operating leases 3.8 % 4.0 % Finance leases 4.7 % 4.5 %
Schedule of Maturity Analysis of Future Undiscounted Cash Flows	A maturity analysis of the future undiscounted cash flows associated with the Company’s operating and finance lease liabilities as of September 30, 2020 is as follows (in thousands): Operating Leases Finance Leases 2020 (remaining) $ 11,735 $ 381 2021 58,792 1,291 2022 53,521 735 2023 46,386 316 2024 36,502 8 Thereafter 55,471 - Total lease payments 262,407 2,731 Less: imputed interest (24,427 ) (139 ) Total present value of lease liabilities $ 237,980 $ 2,592

Goodwill (Tables)

Goodwill (Tables)	9 Months Ended
	Sep. 30, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Summary of Changes in Carrying Value of Goodwill by Reporting Segment	The following table summarizes the changes in the carrying value of goodwill by reporting segment at September 30, 2020 and December 31, 2019 (in thousands): December 31, 2019 Foreign Exchange September 30, 2020 Federal Solutions $ 975,405 $ - $ 975,405 Critical Infrastructure 72,020 (972 ) 71,048 Total $ 1,047,425 $ (972 ) $ 1,046,453

Intangible Assets (Tables)

Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Gross Amount and Accumulated Amortization of Intangible Assets	The gross amount and accumulated amortization of intangible assets with finite useful lives included in “Intangible assets, net” on the consolidated balance sheets are as follows (in thousands except for years): September 30, 2020 December 31, 2019 Weighted Average Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Amortization Period (in years) Backlog $ 109,255 $ (97,713 ) $ 11,542 $ 109,255 $ (87,510 ) $ 21,745 3 Customer relationships 228,529 (99,646 ) 128,883 228,529 (67,809 ) 160,720 7 Leases 670 (594 ) 76 670 (580 ) 90 5 Developed technology 110,939 (61,902 ) 49,037 110,939 (40,749 ) 70,190 4 Trade name 8,200 (7,392 ) 808 8,200 (5,667 ) 2,533 1 Non-compete agreements 3,600 (1,750 ) 1,850 3,600 (925 ) 2,675 3 In process research and development 1,800 - 1,800 1,800 - 1,800 n/a Other intangibles 275 (189 ) 86 275 (170 ) 105 10 Total intangible assets $ 463,268 $ (269,186 ) $ 194,082 $ 463,268 $ (203,410 ) $ 259,858
Schedule of Estimated Amortization Expense	Estimated amortization expense for the remainder of the current fiscal year and in each of the next four years and beyond is as follows (in thousands): September 30, 2020 2020 (remaining) $ 20,820 2021 81,573 2022 36,098 2023 23,549 2024 9,098 Thereafter 21,144 Total $ 192,282

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	9 Months Ended
	Sep. 30, 2020
Property Plant And Equipment [Abstract]
Schedule of Property and Equipment, Net	Property and equipment consisted of the following at September 30, 2020 and December 31, 2019 (in thousands): September 30, 2020 December 31, 2019 Useful life (years) Buildings and leasehold improvements $ 93,361 $ 81,065 1-15 Furniture and equipment 92,199 91,720 3-10 Computer systems and equipment 173,606 164,161 3-10 Construction equipment 9,477 11,765 5-7 368,643 348,711 Accumulated depreciation (247,157 ) (225,960 ) Property and equipment, net $ 121,486 $ 122,751

Debt and Credit Facilities (Tab

Debt and Credit Facilities (Tables)	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Schedule of Long Term Debt	Debt consisted of the following (in thousands): September 30, 2020 December 31, 2019 Short-Term: Senior notes $ 50,000 $ - Total Short-Term 50,000 - Long-Term: Senior notes 200,000 250,000 Convertible senior notes 400,000 - Debt discount (53,692 ) - Debt issuance costs (9,189 ) (647 ) Total long-term 537,119 249,353 Total Debt $ 587,119 $ 249,353
Schedule of Aggregate Amount of Debt	On July 1, 2014, the Company finalized a private placement whereby the Company raised an aggregate amount of $250.0 million in debt as follows (in thousands): Tranche Debt Amount Maturity Date Interest Rates Senior Note, Series A $ 50,000 July 15, 2021 4.44 % Senior Note, Series B 100,000 July 15, 2024 4.98 % Senior Note, Series C 60,000 July 15, 2026 5.13 % Senior Note, Series D 40,000 July 15, 2029 5.38 %
Summary of Convertible Senior Notes	A summary as of September 30, 2020 of the gross carrying amount, unamortized debt discount including debt issuance costs, and net carrying value of the liability component of the Convertible Senior Notes is as follows: September 30, 2020 Par value $ 400,000 Debt discount $ (62,376 ) Carrying amount $ 337,624 Equity component $ 53,552

Investments in and Advances t_2

Investments in and Advances to Joint Ventures (Tables)	9 Months Ended
	Sep. 30, 2020
Equity Method Investments And Joint Ventures [Abstract]
Schedule of Financial Information of Consolidated Joint Ventures	The following represents financial information for consolidated joint ventures included in the consolidated financial statements (in thousands): September 30, 2020 December 31, 2019 Current assets $ 343,304 $ 255,167 Noncurrent assets 2,935 2,860 Total assets 346,239 258,027 Current liabilities 260,175 193,583 Total liabilities 260,175 193,583 Total joint venture equity $ 86,064 $ 64,444 Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Revenue $ 117,344 $ 117,611 $ 335,511 $ 341,719 Costs 105,223 108,839 304,308 322,826 Net income $ 12,121 $ 8,772 $ 31,203 $ 18,893 Net income attributable to noncontrolling interests $ 5,862 $ 4,481 $ 15,086 $ 8,012
Summary of Financial Information for Unconsolidated Joint Ventures	The following represents the financial information of the Company’s unconsolidated joint ventures as presented in their unaudited financial statements (in thousands): September 30, 2020 December 31, 2019 Current assets $ 792,763 $ 801,335 Noncurrent assets 567,919 564,160 Total assets 1,360,682 1,365,495 Current liabilities 753,623 655,495 Noncurrent liabilities 493,576 507,131 Total liabilities 1,247,199 1,162,626 Total joint venture equity $ 113,483 $ 202,869 Investments in and advances to unconsolidated joint ventures $ 71,289 $ 68,620 Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Revenue $ 594,640 $ 474,600 $ 1,286,087 $ 1,225,284 Costs 551,624 452,001 1,202,315 1,166,008 Net income $ 43,016 $ 22,599 $ 83,772 $ 59,276 Equity in earnings of unconsolidated joint ventures $ 16,741 $ 7,274 $ 26,624 $ 29,305

Related Party Transactions (Tab

Related Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2020
Related Party Transactions [Abstract]
Schedule of Consolidated Balance Sheet Related to Services Provided to Unconsolidated Joint Ventures	Amounts included in the consolidated balance sheets related to services the Company provided to unconsolidated joint ventures are as follows (in thousands): September 30, 2020 December 31, 2019 Accounts receivable $ 35,838 $ 37,425 Contract assets 5,703 6,955 Contract liabilities 3,352 4,509

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Schedule of Weighted Average Number of Shares Used To Compute Basic and Diluted EPS	The weighted average number of shares used to compute basic and diluted EPS were: Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Basic weighted average number of shares outstanding 100,736,862 99,434,877 100,700,498 89,977,493 Equity-based awards 378,486 - 321,070 - Convertible senior notes 4,458,265 - - - Diluted weighted average number of shares outstanding 105,573,613 99,434,877 101,021,568 89,977,493
Net Income Available to Shareholders to Compute Basic and Diluted EPS	The net income available to shareholders to compute basic and diluted EPS were (in thousands): Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Net income attributable to Parsons Corporation 40,658 56,812 76,930 106,812 Convertible senior notes if-converted method interest adjustment 1,164 - - - Diluted net income attributable to Parsons Corporation 41,822 56,812 76,930 106,812

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Summary of Business Segment Information	The following table summarizes business segment revenue for the periods presented (in thousands): Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Federal Solutions revenue $ 498,156 $ 486,175 $ 1,457,937 $ 1,387,484 Critical Infrastructure revenue 506,080 537,102 1,496,751 1,529,940 Total revenue $ 1,004,236 $ 1,023,277 $ 2,954,688 $ 2,917,424
Summary of Adjusted EBITDA Business Segment Information	The following table reconciles business segment Adjusted EBITDA attributable to Parsons Corporation to Net Income attributable to Parsons Corporation for the periods presented (in thousands): Three Months Ended Nine Months Ended Adjusted EBITDA attributable to Parsons Corporation September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Federal Solutions $ 45,874 $ 50,359 $ 125,191 $ 126,658 Critical Infrastructure 48,856 33,976 111,732 102,177 Adjusted EBITDA attributable to Parsons Corporation 94,730 84,335 236,923 228,835 Adjusted EBITDA attributable to noncontrolling interests 6,071 4,655 15,535 8,384 Depreciation and amortization (30,952 ) (31,027 ) (95,442 ) (92,692 ) Interest expense, net (5,387 ) (4,482 ) (13,144 ) (18,448 ) Income tax (expense) benefit (16,017 ) 15,453 (32,992 ) 67,063 Equity-based compensation income (expense) 991 1,657 (4,142 ) (45,504 ) Transaction-related costs (a) (2,411 ) (9,891 ) (11,937 ) (26,961 ) Restructuring expense (b) (365 ) (309 ) (1,475 ) (2,880 ) Other (c) (140 ) 902 (1,310 ) (2,973 ) Net income including noncontrolling interests 46,520 61,293 92,016 114,824 Net income attributable to noncontrolling interests 5,862 4,481 15,086 8,012 Net income attributable to Parsons Corporation $ 40,658 $ 56,812 $ 76,930 $ 106,812 (a) Reflects costs incurred in connection with acquisitions, the IPO, and other non-recurring transaction costs, primarily fees paid for professional services and employee retention. (b) Reflects costs associated with corporate restructuring initiatives. (c) Includes a combination of gain/loss related to sale of fixed assets, software implementation costs, and other individually insignificant items that are non-recurring in nature.
Summary of Revenues and Property and Equipment, Net by Geographic Area	The following tables present revenues and property and equipment, net by geographic area (in thousands): Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Revenue North America $ 831,367 $ 849,839 $ 2,429,357 $ 2,400,124 Middle East 168,043 169,028 511,591 504,604 Rest of World 4,826 4,410 13,740 12,696 Total Revenue $ 1,004,236 $ 1,023,277 $ 2,954,688 $ 2,917,424 The geographic location of revenue is determined by the location of the customer. September 30, 2020 December 31, 2019 Property and Equipment, Net North America $ 116,805 $ 117,606 Middle East 4,681 5,145 Total Property and Equipment, Net $ 121,486 $ 122,751
Summary of Revenues by Business Lines	The following table presents revenues by business lines (in thousands): Three Months Ended Nine Months Ended September 30, 2020 September 30, 2019 September 30, 2020 September 30, 2019 Revenue Space & Geospatial Solutions $ 68,354 $ 49,944 $ 177,609 $ 161,469 Cyber & Intelligence 110,339 91,854 312,214 244,892 Engineered Systems 164,867 180,171 504,182 493,065 Missile Defense & C5ISR 154,596 164,206 463,932 488,058 Federal Solutions revenues 498,156 486,175 1,457,937 1,387,484 Mobility Solutions 389,714 435,749 1,180,125 1,211,571 Connected Communities 116,366 101,353 316,626 318,369 Critical Infrastructure revenues 506,080 537,102 1,496,751 1,529,940 Total Revenue $ 1,004,236 $ 1,023,277 $ 2,954,688 $ 2,917,424

Description of Operations - Add

Description of Operations - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	May 31, 2019	May 14, 2019	May 08, 2019	Apr. 15, 2019
Description Of Operations Disclosure [Line Items]
Funds to dividend through public offering		$ 52.1
Repayment on term loan through public offering		$ 150
Common stock dividend ratio				200.00%
Dividends payment, date				May 8, 2019
IPO | Common Stock
Description Of Operations Disclosure [Line Items]
Common stock shares sold			18,518,500
Common stock sold per share			$ 27
Share price		$ 25.515
Proceeds from IPO		$ 536.9
Underwriters | Common Stock
Description Of Operations Disclosure [Line Items]
Purchase of additional shares upon exercise of options	2,777,775
Underwriting discount per share		$ 1.485
Proceeds from IPO		$ 536.9

Basis of Presentation and Pri_3

Basis of Presentation and Principles of Consolidation - Additional Information (Details)	3 Months Ended
	Jun. 30, 2020
Employee Stock Purchase Plan | Maximum
Basis Of Presentation And Principles Of Consolidation Disclosure [Line Items]
Percentage of per-share market value limit for share purchases	5.00%

New Accounting Pronouncements -

New Accounting Pronouncements - Additional Information (Details) - ASU 2016-13	Sep. 30, 2020
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Change in accounting principle, accounting standards update, adoption date	Jan. 1, 2020
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, immaterial effect	true

Acquisitions - Additional Infor

Acquisitions - Additional Information (Details) - USD ($) $ in Thousands	Jul. 31, 2019	Jan. 07, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Business Acquisition [Line Items]
Amortization of intangible assets			$ 20,900	$ 22,100	$ 65,700	$ 64,500
Goodwill			1,046,453		1,046,453		$ 1,047,425
Revenues			1,004,236	1,023,277	2,954,688	2,917,424
OGSystems
Business Acquisition [Line Items]
Percentage of ownership interest acquired		100.00%
Cash paid to acquire		$ 292,400
Borrowed under credit agreement to partially fund the acquisition		110,000
Amortization of intangible assets			5,900	5,900	17,800	17,800
Goodwill		183,540
Goodwill deductible for tax purposes		16,000
Revenues			46,200	33,700	117,000	108,700
OGSystems | Indirect, General and Administrative Expense
Business Acquisition [Line Items]
Acquisition related expenses							5,400
OGSystems | Term Loan
Business Acquisition [Line Items]
Borrowed under credit agreement to partially fund the acquisition		$ 150,000
QRC Technologies
Business Acquisition [Line Items]
Percentage of ownership interest acquired	100.00%
Cash paid to acquire	$ 214,100
Amortization of intangible assets			3,500	1,900	10,600	1,900
Goodwill	125,091
Revenues			$ 12,600	$ 5,600	$ 25,200	$ 5,600
QRC Technologies | Revolving Credit Facility
Business Acquisition [Line Items]
Borrowed under credit agreement to partially fund the acquisition	$ 140,000
QRC Technologies | Indirect, General and Administrative Expense
Business Acquisition [Line Items]
Acquisition related expenses							$ 4,900

Acquisitions - Summary of Estim

Acquisitions - Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed on Preliminary Purchase Price Allocation (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Jul. 31, 2019	Jan. 07, 2019
Business Acquisition [Line Items]
Contract assets	$ 610,893	$ 575,089
Goodwill	1,046,453	1,047,425
Contract liabilities	$ (212,373)	$ (230,681)
OGSystems
Business Acquisition [Line Items]
Cash and cash equivalents				$ 5,772
Accounts receivable				9,904
Contract assets				9,747
Prepaid expenses and other current assets				4,307
Property and equipment				4,085
Right of use assets, operating leases				8,826
Goodwill				183,540
Intangible assets				92,300
Other noncurrent assets				10
Accounts payable				(5,450)
Accrued expenses and other current liabilities				(7,147)
Contract liabilities				(1,300)
Short-term lease liabilities, operating leases				(805)
Income tax payable				(1,178)
Deferred tax liabilities				(1,195)
Long-term lease liabilities, operating leases				(8,021)
Other long-term liabilities				(1,015)
Net assets acquired				$ 292,380
QRC Technologies
Business Acquisition [Line Items]
Cash and cash equivalents			$ 5,925
Accounts receivable			5,587
Prepaid expenses and other current assets			5,727
Property and equipment			1,205
Right of use assets, operating leases			5,228
Goodwill			125,091
Intangible assets			76,200
Accounts payable			(1,567)
Accrued expenses and other current liabilities			(4,025)
Short-term lease liabilities, operating leases			(545)
Long-term lease liabilities, operating leases			(4,683)
Net assets acquired			$ 214,143

Acquisitions - Schedule of Inta

Acquisitions - Schedule of Intangible Assets Value on Purchase Price (Details) - USD ($) $ in Thousands	Jul. 31, 2019	Jan. 07, 2019	Sep. 30, 2020
Customer Relationships
Acquired Finite Lived Intangible Assets [Line Items]
Amortization Period (in years)			7 years
Customer Relationships | OGSystems
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount		$ 57,100
Amortization Period (in years)		5 years
Customer Relationships | QRC Technologies
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 49,800
Amortization Period (in years)	12 years
Backlog
Acquired Finite Lived Intangible Assets [Line Items]
Amortization Period (in years)			3 years
Backlog | OGSystems
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount		$ 27,700
Amortization Period (in years)		3 years
Backlog | QRC Technologies
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 800
Amortization Period (in years)	1 year
Trade Name
Acquired Finite Lived Intangible Assets [Line Items]
Amortization Period (in years)			1 year
Trade Name | OGSystems
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount		$ 3,800
Amortization Period (in years)		2 years
Trade Name | QRC Technologies
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 800
Amortization Period (in years)	2 years
Non compete Agreements
Acquired Finite Lived Intangible Assets [Line Items]
Amortization Period (in years)			3 years
Non compete Agreements | OGSystems
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount		$ 2,400
Amortization Period (in years)		3 years
Non compete Agreements | QRC Technologies
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,200
Amortization Period (in years)	4 years
Developed Technologies
Acquired Finite Lived Intangible Assets [Line Items]
Amortization Period (in years)			4 years
Developed Technologies | OGSystems
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount		$ 1,300
Amortization Period (in years)		3 years
Developed Technologies | QRC Technologies
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 21,800
Developed Technologies | QRC Technologies | Minimum
Acquired Finite Lived Intangible Assets [Line Items]
Amortization Period (in years)	3 years
Developed Technologies | QRC Technologies | Maximum
Acquired Finite Lived Intangible Assets [Line Items]
Amortization Period (in years)	5 years
In-Process Research and Development | QRC Technologies
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,800
In-Process Research and Development | QRC Technologies | Minimum
Acquired Finite Lived Intangible Assets [Line Items]
Amortization Period (in years)	3 years
In-Process Research and Development | QRC Technologies | Maximum
Acquired Finite Lived Intangible Assets [Line Items]
Amortization Period (in years)	5 years

Acquisitions - Schedule of Supp

Acquisitions - Schedule of Supplemental Pro Forma Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
OGSystems
Business Acquisition [Line Items]
Pro forma revenue	$ 1,004,236	$ 1,023,277	$ 2,954,688	$ 2,919,379
Pro forma net income including noncontrolling interests	47,561	61,293	95,189	118,896
QRC Technologies
Business Acquisition [Line Items]
Pro forma revenue	1,004,236	1,026,831	2,954,688	2,938,973
Pro forma net income including noncontrolling interests	$ 47,618	$ 65,782	$ 95,994	$ 117,399

Contracts with Customers - Summ

Contracts with Customers - Summary of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation Of Revenue [Line Items]
Revenues	$ 1,004,236	$ 1,023,277	$ 2,954,688	$ 2,917,424
Fixed-Price
Disaggregation Of Revenue [Line Items]
Revenues	324,901	288,316	944,577	850,658
Time-and-Materials
Disaggregation Of Revenue [Line Items]
Revenues	265,987	285,586	777,807	810,656
Cost-Plus
Disaggregation Of Revenue [Line Items]
Revenues	$ 413,348	$ 449,375	$ 1,232,304	$ 1,256,110

Contracts with Customers - Su_2

Contracts with Customers - Summary of Contract Assets and Contract Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Revenue From Contract With Customer [Abstract]
Contract assets	$ 610,893	$ 575,089
Contract liabilities	212,373	230,681
Net contract assets (liabilities)	398,520	$ 344,408
Change in contract assets	35,804
Change in contract liabilities	(18,308)
Change in contract assets and liabilities	$ 54,112
Percentage change in contract assets	6.20%
Percentage change in contract liabilities	(7.90%)
Percentage change in contract assets and liabilities	15.70%

Contracts with Customers - Su_3

Contracts with Customers - Summary of Contract Assets and Contract Liabilities (Parenthetical) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Revenue From Contract With Customer [Abstract]
Contract retentions	$ 89.8	$ 85.5
Contract retentions, not expected to be paid in next 12 months	42
Contract assets, unapproved change orders, claims, and requests	$ 96.2	$ 73

Contracts with Customers - Addi

Contracts with Customers - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue From Contract With Customer [Abstract]
Revenue recognized included contract liability	$ 9,500,000	$ 2,100,000	$ 132,200,000	$ 115,100,000
Impairment of contract assets	0	$ 0	0	$ 0
Impact of changes in estimated claims or incentives on revenue	5,000,000		5,000,000
Remaining unsatisfied performance obligations	$ 5,000,000,000		$ 5,000,000,000

Contracts with Customers - Su_4

Contracts with Customers - Summary of Changes in Contract Assets and Contract Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Revenue From Contract With Customer [Abstract]
Acquired contract assets	$ 0	$ 9,747
Acquired contract liabilities	0	1,300
Change in the estimate of variable consideration	$ 0	$ 12,166

Contracts with Customers - Su_5

Contracts with Customers - Summary of Changes in Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue From Contract With Customer [Abstract]
Revenue impact, net	$ (134)	$ 9,116	$ 8,848	$ 9,116

Contracts with Customers - Su_6

Contracts with Customers - Summary of Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Revenue From Contract With Customer [Abstract]
Billed	$ 527,654	$ 475,528
Unbilled	252,963	201,461
Total accounts receivable, gross	780,617	676,989
Allowance for doubtful accounts	(5,557)	(5,497)
Total accounts receivable, net	$ 775,060	$ 671,492

Contracts with Customers - Su_7

Contracts with Customers - Summary of Remaining Unsatisfied Performance Obligations Expect to Satisfy (Details) $ in Thousands	Sep. 30, 2020USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 5,000,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-10-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 2,583,216
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 1,079,618
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 1,310,642
Revenue, remaining performance obligation, expected timing of satisfaction, period
Federal Solution Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-10-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 1,174,719
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Federal Solution Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 379,069
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Federal Solution Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 560,850
Revenue, remaining performance obligation, expected timing of satisfaction, period
Critical Infrastructure | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-10-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 1,408,497
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Critical Infrastructure | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 700,549
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Critical Infrastructure | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 749,792
Revenue, remaining performance obligation, expected timing of satisfaction, period

Leases - Additional Information

Leases - Additional Information (Details)	9 Months Ended
	Sep. 30, 2020USD ($)
Lessee Lease Description [Line Items]
Lease option to extend	five years
Lease existence of option to extend	true
Lease option to terminate	third year
Lease existence of option to terminate	true
Operating lease not yet commenced expense	$ 0
Minimum
Lessee Lease Description [Line Items]
Lease term of contract	1 year
Maximum
Lessee Lease Description [Line Items]
Lease term of contract	10 years

Leases - Summary of Lease Costs

Leases - Summary of Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Operating lease cost	$ 15,919	$ 17,969	$ 48,945	$ 53,835
Short-term lease cost	4,301	5,429	12,254	10,925
Amortization of right-of-use assets	531	120	1,036	455
Interest on lease liabilities	64	15	109	46
Sublease income	(959)	(712)	(2,771)	(2,727)
Total lease cost	$ 19,856	$ 22,821	$ 59,573	$ 62,534

Leases - Schedule of Supplement

Leases - Schedule of Supplemental Cash Flow Information Related to Leases (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Operating cash flows for operating leases	$ 45,343	$ 52,056
Operating cash flows for financing activities	111	46
Financing cash flows from finance leases	1,080	524
Right-of-use assets obtained in exchange for new operating lease liabilities	19,587	274,212
Right-of-use assets obtained in exchange for new finance lease liabilities	$ 0	$ 1,818

Leases - Schedule of Suppleme_2

Leases - Schedule of Supplemental Balance Sheet and Other Information Related to Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Operating Leases:
Right-of-use assets	$ 212,592	$ 233,415
Lease liabilities:
Current	48,661	49,994
Long-term	189,319	203,624
Total operating lease liabilities	237,980	253,618
Finance Leases:
Other noncurrent assets	2,757	2,377
Accrued expenses and other current liabilities	$ 1,345	$ 1,075
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	psn:AccruedExpensesAndOtherCurrentLiabilities	psn:AccruedExpensesAndOtherCurrentLiabilities
Other long-term liabilities	$ 1,247	$ 1,202
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Weighted Average Remaining Lease Term:
Operating leases	5 years	6 years
Finance leases	2 years	3 years
Weighted Average Discount Rate:
Operating leases	3.80%	4.00%
Finance leases	4.70%	4.50%

Leases - Schedule of Maturity A

Leases - Schedule of Maturity Analysis of Future Undiscounted Cash Flows (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Operating Leases
2020 (remaining)	$ 11,735
2021	58,792
2022	53,521
2023	46,386
2024	36,502
Thereafter	55,471
Total lease payments	262,407
Less: imputed interest	(24,427)
Total present value of lease liabilities	237,980	$ 253,618
Finance Leases
2020 (remaining)	381
2021	1,291
2022	735
2023	316
2024	8
Thereafter	0
Total lease payments	2,731
Less: imputed interest	(139)
Total present value of lease liabilities	$ 2,592

Goodwill - Summary of Changes i

Goodwill - Summary of Changes in Carrying Value of Goodwill by Reporting Segment (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)
Goodwill [Line Items]
Beginning Balance	$ 1,047,425
Foreign Exchange	(972)
Ending Balance	1,046,453
Federal Solutions
Goodwill [Line Items]
Beginning Balance	975,405
Foreign Exchange	0
Ending Balance	975,405
Critical Infrastructure
Goodwill [Line Items]
Beginning Balance	72,020
Foreign Exchange	(972)
Ending Balance	$ 71,048

Goodwill - Additional Informati

Goodwill - Additional Information (Details)	9 Months Ended
	Sep. 30, 2020USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
Impairment of goodwill	$ 0

Intangible Assets - Schedule of

Intangible Assets - Schedule of Gross Amount and Accumulated Amortization of Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 463,268	$ 463,268
Accumulated Amortization	(269,186)	(203,410)
Net Carrying Amount	194,082	259,858
Backlog
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	109,255	109,255
Accumulated Amortization	(97,713)	(87,510)
Net Carrying Amount	$ 11,542	21,745
Amortization Period (in years)	3 years
Customer Relationships
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 228,529	228,529
Accumulated Amortization	(99,646)	(67,809)
Net Carrying Amount	$ 128,883	160,720
Amortization Period (in years)	7 years
Leases
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 670	670
Accumulated Amortization	(594)	(580)
Net Carrying Amount	$ 76	90
Amortization Period (in years)	5 years
Developed Technology
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 110,939	110,939
Accumulated Amortization	(61,902)	(40,749)
Net Carrying Amount	$ 49,037	70,190
Amortization Period (in years)	4 years
Trade Name
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 8,200	8,200
Accumulated Amortization	(7,392)	(5,667)
Net Carrying Amount	$ 808	2,533
Amortization Period (in years)	1 year
Non compete Agreements
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 3,600	3,600
Accumulated Amortization	(1,750)	(925)
Net Carrying Amount	$ 1,850	2,675
Amortization Period (in years)	3 years
In Process Research and Development
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,800	1,800
Accumulated Amortization		0
Net Carrying Amount	1,800	1,800
Other Intangibles
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	275	275
Accumulated Amortization	(189)	(170)
Net Carrying Amount	$ 86	$ 105
Amortization Period (in years)	10 years

Intangible Assets - Additional

Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization expense of intangible assets	$ 20.9	$ 22.1	$ 65.7	$ 64.5

Intangible Assets - Schedule _2

Intangible Assets - Schedule of Estimated Amortization Expense (Details) $ in Thousands	Sep. 30, 2020USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
2020 (remaining)	$ 20,820
2021	81,573
2022	36,098
2023	23,549
2024	9,098
Thereafter	21,144
Finite-Lived Intangible Assets, Net	$ 192,282

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 368,643	$ 348,711
Accumulated depreciation	(247,157)	(225,960)
Property and equipment, net	121,486	122,751
Buildings and Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 93,361	81,065
Buildings and Leasehold Improvements | Minimum
Property Plant And Equipment [Line Items]
Useful life (years)	1 year
Buildings and Leasehold Improvements | Maximum
Property Plant And Equipment [Line Items]
Useful life (years)	15 years
Furniture and Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 92,199	91,720
Furniture and Equipment | Minimum
Property Plant And Equipment [Line Items]
Useful life (years)	3 years
Furniture and Equipment | Maximum
Property Plant And Equipment [Line Items]
Useful life (years)	10 years
Computer Systems and Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 173,606	164,161
Computer Systems and Equipment | Minimum
Property Plant And Equipment [Line Items]
Useful life (years)	3 years
Computer Systems and Equipment | Maximum
Property Plant And Equipment [Line Items]
Useful life (years)	10 years
Construction Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 9,477	$ 11,765
Construction Equipment | Minimum
Property Plant And Equipment [Line Items]
Useful life (years)	5 years
Construction Equipment | Maximum
Property Plant And Equipment [Line Items]
Useful life (years)	7 years

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Property Plant And Equipment [Abstract]
Depreciation expense	$ 9.5	$ 8.9	$ 28.9	$ 28.2

Debt and Credit Facilities - Sc

Debt and Credit Facilities - Schedule of Long Term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Short-term debt	$ 50,000	$ 0
Convertible senior notes	400,000
Debt discount	(53,692)
Long-Term Debt issuance costs	(9,189)	(647)
Total long-term	537,119	249,353
Total Debt	587,119	249,353
Senior Notes
Debt Instrument [Line Items]
Short-Term	50,000
Long-term debt	$ 200,000	$ 250,000

Debt and Credit Facilities - Ad

Debt and Credit Facilities - Additional Information (Details)	May 10, 2019USD ($)	Jul. 01, 2014USD ($)	Aug. 31, 2020USD ($)Day$ / sharesshares	Sep. 30, 2020USD ($)$ / shares	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)Day$ / sharesshares	Sep. 30, 2019USD ($)	Dec. 31, 2020USD ($)	Aug. 10, 2020USD ($)	Dec. 31, 2019USD ($)	Jan. 31, 2019USD ($)
Debt Instrument [Line Items]
Letters of credit outstanding amount				$ 198,000,000		$ 198,000,000				$ 197,300,000
Proceeds from issuance of warrants						13,808,000	$ 0
Deferred tax liabilities				9,273,000		9,273,000				9,621,000
Deferred tax assets				130,904,000		130,904,000				130,401,000
Level 2
Debt Instrument [Line Items]
Senior notes, fair value				277,600,000		277,600,000
Senior Notes
Debt Instrument [Line Items]
Debt instrument, outstanding amount				200,000,000		200,000,000				250,000,000
Convertible Senior Notes
Debt Instrument [Line Items]
Interest rate			0.25%
Interest expense				1,500,000		1,500,000
Debt Amount			$ 400,000,000	400,000,000		400,000,000
Interest expense				1,500,000		$ 1,500,000
Exercise of option by initial purchasers aggregate principal amount			50,000,000
Proceeds from issuance and sale of debt			389,700,000
Transaction fees and other third-party offering expenses			$ 10,300,000
Debt instrument, payment terms						The Convertible Senior Notes accrue interest at a rate of 0.25% per annum, payable semi-annually on February 15 and August 15 of each year beginning on February 15, 2021
Debt instrument, frequency of periodic payment						semi-annually
Maturity Date			Aug. 15, 2025
Convertible note converted each amount				$ 1,000		$ 1,000
Convertible notes converted each into shares of common stock | shares						22.2913
Debt Instrument, conversion price | $ / shares				$ 44.86		$ 44.86
Threshold trading days | Day			20			51
Threshold consecutive trading days | Day			30
Conversion percentage of stock price trigger			130.00%
Number of business day period			5 days
Consecutive trading day period			5 days
Convertible principal amount			$ 1,000
Measurement period, percentage			98.00%
Percentage of principal amount to redeem convertible senior notes			100.00%
Percentage of convertible senior notes repurchased at cash			100.00%
Debt liability			$ 336,100,000
Debt instrument convertible notes additional paid in capital			$ 53,600,000
Convertible senior notes effective interest rate			3.25%
Net carrying value of notes				$ 337,624,000		$ 337,624,000
Bond hedge term						5 years
Number of shares issuable upon conversion | shares			8,900,000
Cost of convertible note hedge transaction			$ 55,000,000
Number of common stock acquired by offsetting sale warrants. | shares						8,900,000
Exercise price of warrants | $ / shares				$ 66.46		$ 66.46
Proceeds from issuance of warrants						$ 13,800,000
Convertible Note Hedge And Warrant Transaction
Debt Instrument [Line Items]
Purchase of bond hedges and sale of warrants			$ 41,200,000
Deferred tax liabilities				$ 16,200,000		16,200,000
Deferred tax assets				16,500,000		16,500,000
Term Loan
Debt Instrument [Line Items]
Interest expense					$ 0		2,300,000
Repayment of outstanding balance	$ 150,000,000
Debt Amount											$ 150,000,000
Interest expense					0		2,300,000
Forecast | Term Loan
Debt Instrument [Line Items]
Debt instrument, outstanding amount								$ 0
Private Placement
Debt Instrument [Line Items]
Debt issuance costs incurred				1,100,000		1,100,000			$ 500,000
Repayment of outstanding balance		$ 250,000,000
Private Placement | Accrued Expenses and Other Current Liabilities
Debt Instrument [Line Items]
Interest payable				2,400,000		2,400,000				2,600,000
Private Placement | Senior Notes
Debt Instrument [Line Items]
Interest expense				3,100,000	3,100,000	9,300,000	9,300,000
Interest expense				3,100,000	3,100,000	9,300,000	9,300,000
Interest payments				6,200,000	6,200,000	$ 12,400,000	12,400,000
Minimum | Convertible Senior Notes
Debt Instrument [Line Items]
Debt Instrument, conversion price | $ / shares			$ 44.86
Percentage of bond hedge and warrant transactions increased conversion price			35.00%
Maximum | Convertible Senior Notes
Debt Instrument [Line Items]
Debt Instrument, conversion price | $ / shares			$ 66.46
Percentage of bond hedge and warrant transactions increased conversion price			100.00%
Revolving Credit Facility
Debt Instrument [Line Items]
Amended and restated credit agreement date						Nov. 30, 2017
Debt issuance costs incurred				2,000,000		$ 2,000,000
Revolving credit facility				500,000,000		500,000,000
Increase in revolving credit facility				550,000,000		$ 550,000,000
Credit agreement extended date						Nov. 30, 2022
Letters of credit outstanding amount				44,900,000		$ 44,900,000				$ 43,700,000
Interest expense				200,000	1,100,000	900,000	6,400,000
Debt instrument, outstanding amount				0		0
Interest expense				$ 200,000	$ 1,100,000	$ 900,000	$ 6,400,000
Revolving Credit Facility | Minimum
Debt Instrument [Line Items]
Interest rate				1.44%		1.44%
Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Interest rate										3.02%
Revolving Credit Facility | Base Rate | Minimum
Debt Instrument [Line Items]
Margin interest rate						0.125%
Revolving Credit Facility | Base Rate | Maximum
Debt Instrument [Line Items]
Margin interest rate						1.00%
Revolving Credit Facility | LIBOR | Minimum
Debt Instrument [Line Items]
Margin interest rate						1.125%
Revolving Credit Facility | LIBOR | Maximum
Debt Instrument [Line Items]
Margin interest rate						2.00%

Debt and Credit Facilities - _2

Debt and Credit Facilities - Schedule of Aggregate Amount of Debt (Details) - Private Placement $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)
Senior Note, Series A
Debt Instrument [Line Items]
Debt Amount	$ 50,000
Maturity Date	Jul. 15, 2021
Interest Rates	4.44%
Senior Note, Series B
Debt Instrument [Line Items]
Debt Amount	$ 100,000
Maturity Date	Jul. 15, 2024
Interest Rates	4.98%
Senior Note, Series C
Debt Instrument [Line Items]
Debt Amount	$ 60,000
Maturity Date	Jul. 15, 2026
Interest Rates	5.13%
Senior Note, Series D
Debt Instrument [Line Items]
Debt Amount	$ 40,000
Maturity Date	Jul. 15, 2029
Interest Rates	5.38%

Debt and Credit Facilities - Su

Debt and Credit Facilities - Summary of Convertible Senior Notes (Details) - Convertible Senior Notes - USD ($) $ in Thousands	Sep. 30, 2020	Aug. 31, 2020
Debt Instrument [Line Items]
Debt Amount	$ 400,000	$ 400,000
Debt discount	(62,376)
Carrying amount	337,624
Equity component	$ 53,552

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Millions	Mar. 27, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Mar. 26, 2020	Dec. 31, 2019
Income Taxes [Line Items]
Liability for income taxes associated with uncertain tax positions		$ 14.7		$ 14.7			$ 15.5
Decrease in uncertain tax positions during the next twelve months		$ 1		$ 1
Effective income tax rate		25.61%	(33.71%)	26.39%	(140.42%)
Tax benefit from the remeasurement of deferred taxes due to change in effective tax rate			$ 29
U.S. corporate tax rate		21.00%
Deferred tax assets valuation allowance		$ 17.5		$ 17.5
CARES Act
Income Taxes [Line Items]
Percentage of net operating loss (NOL) carryovers to offset of taxable income	100.00%
Allowable business interest deduction percentage of adjusted taxable income	50.00%					30.00%
Operating loss carryforwards description				In addition, the CARES Act allows NOLs
CARES Act | OGSystems
Income Taxes [Line Items]
Net operating loss carryforwards, tax refund claim related to acquisition	$ 3.9

Contingencies - Additional Info

Contingencies - Additional Information (Details)	Mar. 01, 2017USD ($)	Sep. 30, 2020Claim
Legal Proceedings [Line Items]
Number of claims outstanding | Claim		0
Minimum
Legal Proceedings [Line Items]
Loss contingency damages value | $	$ 100,000,000

Retirement Benefit Plan - Addit

Retirement Benefit Plan - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	Apr. 15, 2019	Apr. 03, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Shares fully vested, Description					Shares allocated to a participant’s account are fully vested after three years of credited service, or in the event(s) of reaching age 65, death or disability while an active employee of the Company.
Shares fully vested after credited service					3 years
Common stock shares outstanding including ESOP			100,727,574		100,727,574		100,669,694
Company's stock held by ESOP			76,090,531		76,090,531		78,896,806
ESOP dividends declared date		Apr. 3, 2019
ESOP dividends declared per share		$ 2
ESOP dividends declared amount		$ 52.1
ESOP dividends payment date		May 10, 2019
Common stock dividend ratio	200.00%
Dividends declared date	Apr. 15, 2019
Dividends record date	May 7, 2019
Dividends payment, date	May 8, 2019
Direct Costs of Contracts and Indirect, General and Administrative Expense
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
ESOP contribution expense			$ 12.5	$ 12.3	$ 42	$ 36.8

Investments in and Advances t_3

Investments in and Advances to Joint Ventures - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Schedule Of Equity Method Investments [Line Items]
Letters of credit outstanding amount	$ 198		$ 198		$ 197.3
Unconsolidated Joint Ventures
Schedule Of Equity Method Investments [Line Items]
Net distributions from unconsolidated joint ventures	11.2	$ 13.7	23.2	$ 28
Consolidated Joint Ventures
Schedule Of Equity Method Investments [Line Items]
Letters of credit outstanding amount	$ 59.9		$ 59.9		$ 55

Investments in and Advances t_4

Investments in and Advances to Joint Ventures - Summary of Financial Information for Consolidated Joint Ventures (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Schedule Of Equity Method Investments [Line Items]
Current assets	$ 2,081,619		$ 2,081,619		$ 1,526,409
Total assets	3,918,761		3,918,761		3,450,368
Current liabilities	1,246,550		1,246,550		1,144,382
Total liabilities	2,149,290		2,149,290		1,789,612
Total joint venture equity	1,727,497		1,727,497		1,629,890
Revenue	1,004,236	$ 1,023,277	2,954,688	$ 2,917,424
Costs	788,769	798,552	2,307,725	2,297,512
Net income attributable to Parsons Corporation	40,658	56,812	76,930	106,812
Net income attributable to noncontrolling interests	5,862	4,481	15,086	8,012
Consolidated Joint Ventures
Schedule Of Equity Method Investments [Line Items]
Current assets	343,304		343,304		255,167
Noncurrent assets	2,935		2,935		2,860
Total assets	346,239		346,239		258,027
Current liabilities	260,175		260,175		193,583
Total liabilities	260,175		260,175		193,583
Total joint venture equity	86,064		86,064		$ 64,444
Revenue	117,344	117,611	335,511	341,719
Costs	105,223	108,839	304,308	322,826
Net income attributable to Parsons Corporation	12,121	8,772	31,203	18,893
Net income attributable to noncontrolling interests	$ 5,862	$ 4,481	$ 15,086	$ 8,012

Investments in and Advances t_5

Investments in and Advances to Joint Ventures - Summary of Financial Information for Unconsolidated Joint Ventures (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Schedule Of Equity Method Investments [Line Items]
Current assets	$ 2,081,619		$ 2,081,619		$ 1,526,409
Total assets	3,918,761		3,918,761		3,450,368
Current liabilities	1,246,550		1,246,550		1,144,382
Total liabilities	2,149,290		2,149,290		1,789,612
Total joint venture equity	1,727,497		1,727,497		1,629,890
Investments in and advances to unconsolidated joint ventures	71,289		71,289		68,620
Revenue	1,004,236	$ 1,023,277	2,954,688	$ 2,917,424
Costs	788,769	798,552	2,307,725	2,297,512
Net income attributable to Parsons Corporation	40,658	56,812	76,930	106,812
Equity in earnings of unconsolidated joint ventures	16,741	7,274	26,624	29,305
Unconsolidated Joint Ventures
Schedule Of Equity Method Investments [Line Items]
Current assets	792,763		792,763		801,335
Noncurrent assets	567,919		567,919		564,160
Total assets	1,360,682		1,360,682		1,365,495
Current liabilities	753,623		753,623		655,495
Noncurrent liabilities	493,576		493,576		507,131
Total liabilities	1,247,199		1,247,199		1,162,626
Total joint venture equity	113,483		113,483		202,869
Investments in and advances to unconsolidated joint ventures	71,289		71,289		$ 68,620
Revenue	594,640	474,600	1,286,087	1,225,284
Costs	551,624	452,001	1,202,315	1,166,008
Net income attributable to Parsons Corporation	43,016	22,599	83,772	59,276
Equity in earnings of unconsolidated joint ventures	$ 16,741	$ 7,274	$ 26,624	$ 29,305

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - Unconsolidated joint ventures - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Related Party Transaction [Line Items]
Revenues	$ 42	$ 28.8	$ 124.7	$ 113.1
Reimbursable cost incurred	$ 32.3	$ 20.5	$ 98.3	$ 86.3

Related Party Transactions - Sc

Related Party Transactions - Schedule of Consolidated Balance Sheet Related to Services Provided to Unconsolidated Joint Ventures (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Contract assets	$ 610,893	$ 575,089
Contract liabilities	212,373	230,681
Unconsolidated Joint Ventures
Related Party Transaction [Line Items]
Accounts receivable	35,838	37,425
Contract assets	5,703	6,955
Contract liabilities	$ 3,352	$ 4,509

Earnings Per Share - Additional

Earnings Per Share - Additional Information (Details) - shares	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Equity-based Awards
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	205	3,318

Earnings Per Share - Schedule o

Earnings Per Share - Schedule of Weighted Average Number of Shares Used To Compute Basic and Diluted EPS (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Basic weighted average number of shares outstanding	100,736,862	99,434,877	100,700,498	89,977,493
Equity-based awards	378,486	0	321,070	0
Convertible senior notes	4,458,265	0	0	0
Diluted weighted average number of shares outstanding	105,573,613	99,434,877	101,021,568	89,977,493

Earnings Per Share - Net Income

Earnings Per Share - Net Income Available to Shareholders to Compute Basic and Diluted EPS (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Net income attributable to Parsons Corporation	$ 40,658	$ 56,812	$ 76,930	$ 106,812
Convertible senior notes if-converted method interest adjustment	1,164
Diluted net income attributable to Parsons Corporation	$ 41,822	$ 56,812	$ 76,930	$ 106,812

Segment Information - Additiona

Segment Information - Additional Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)segment	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			2
Revenues	$ 1,004,236	$ 1,023,277	$ 2,954,688	$ 2,917,424
Property and equipment, net	121,486		121,486		$ 122,751
United States
Segment Reporting Information [Line Items]
Revenues	774,000	$ 774,200	2,200,000	$ 2,200,000
Property and equipment, net	$ 109,600		$ 109,600		$ 109,900
Federal Solutions
Segment Reporting Information [Line Items]
Changes in reportable segments, description			we realigned the five business lines within our Federal Solutions segment into four business lines.
Critical Infrastructure
Segment Reporting Information [Line Items]
Changes in reportable segments, description			We re-aligned our Critical Infrastructure segment from three markets to two markets.

Segment Information - Summary o

Segment Information - Summary of Business Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Total revenue	$ 1,004,236	$ 1,023,277	$ 2,954,688	$ 2,917,424
Federal Solution Segment
Segment Reporting Information [Line Items]
Total revenue	498,156	486,175	1,457,937	1,387,484
Critical Infrastructure
Segment Reporting Information [Line Items]
Total revenue	$ 506,080	$ 537,102	$ 1,496,751	$ 1,529,940

Segment Information - Summary_2

Segment Information - Summary of Adjusted EBITDA Business Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Adjusted EBITDA attributable to Parsons Corporation
Adjusted EBITDA attributable to Parsons Corporation	$ 94,730	$ 84,335	$ 236,923	$ 228,835
Adjusted EBITDA attributable to noncontrolling interests	6,071	4,655	15,535	8,384
Depreciation and amortization	(30,952)	(31,027)	(95,442)	(92,692)
Interest expense, net	(5,387)	(4,482)	(13,144)	(18,448)
Income tax (expense) benefit	(16,017)	15,453	(32,992)	67,063
Equity-based compensation income (expense)	991	1,657	(4,142)	(45,504)
Transaction-related costs	(2,411)	(9,891)	(11,937)	(26,961)
Restructuring expense	(365)	(309)	(1,475)	(2,880)
Other	(140)	902	(1,310)	(2,973)
Net income including noncontrolling interests	46,520	61,293	92,016	114,824
Net income attributable to noncontrolling interests	5,862	4,481	15,086	8,012
Net income attributable to Parsons Corporation	40,658	56,812	76,930	106,812
Federal Solution Segment
Adjusted EBITDA attributable to Parsons Corporation
Adjusted EBITDA attributable to Parsons Corporation	45,874	50,359	125,191	126,658
Critical Infrastructure
Adjusted EBITDA attributable to Parsons Corporation
Adjusted EBITDA attributable to Parsons Corporation	$ 48,856	$ 33,976	$ 111,732	$ 102,177

Segment Information - Summary_3

Segment Information - Summary of Revenues and Property and Equipment, Net by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Revenues	$ 1,004,236	$ 1,023,277	$ 2,954,688	$ 2,917,424
Property and Equipment, Net	121,486		121,486		$ 122,751
North America
Segment Reporting Information [Line Items]
Revenues	831,367	849,839	2,429,357	2,400,124
Property and Equipment, Net	116,805		116,805		117,606
Middle East
Segment Reporting Information [Line Items]
Revenues	168,043	169,028	511,591	504,604
Property and Equipment, Net	4,681		4,681		$ 5,145
Rest of World
Segment Reporting Information [Line Items]
Revenues	$ 4,826	$ 4,410	$ 13,740	$ 12,696

Segment Information - Summary_4

Segment Information - Summary of Revenues by Business Lines (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Revenues	$ 1,004,236	$ 1,023,277	$ 2,954,688	$ 2,917,424
Federal Solution Segment
Segment Reporting Information [Line Items]
Revenues	498,156	486,175	1,457,937	1,387,484
Federal Solution Segment | Space & Geospatial Solutions
Segment Reporting Information [Line Items]
Revenues	68,354	49,944	177,609	161,469
Federal Solution Segment | Cyber & Intelligence
Segment Reporting Information [Line Items]
Revenues	110,339	91,854	312,214	244,892
Federal Solution Segment | Engineered Systems
Segment Reporting Information [Line Items]
Revenues	164,867	180,171	504,182	493,065
Federal Solution Segment | Missile Defense & C5ISR
Segment Reporting Information [Line Items]
Revenues	154,596	164,206	463,932	488,058
Critical Infrastructure
Segment Reporting Information [Line Items]
Revenues	506,080	537,102	1,496,751	1,529,940
Critical Infrastructure | Mobility Solutions
Segment Reporting Information [Line Items]
Revenues	389,714	435,749	1,180,125	1,211,571
Critical Infrastructure | Connected Communities
Segment Reporting Information [Line Items]
Revenues	$ 116,366	$ 101,353	$ 316,626	$ 318,369

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) $ in Millions	Oct. 29, 2020USD ($)
Braxton Science & Technology Group, LLC | Subsequent Event
Subsequent Event [Line Items]
Estimated purchase price	$ 300