Acquisitions - Additional Information (Detail) € in Millions, shares in Millions		1 Months Ended	3 Months Ended		6 Months Ended
	Apr. 30, 2021 USD ($) shares	Mar. 31, 2017 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Apr. 30, 2021 EUR (€)
Business Acquisition [Line Items]
Net cash outlay after acquiree's cash on hand					$ 138,668,000
Shares issued in connection with acquisition of business					207,169,000
Total revenues			$ 701,354,000	$ 554,278,000	$ 1,366,214,000	$ 1,084,766,000
Euro Infrastructure Co [Member]
Business Acquisition [Line Items]
Equity method investment ownership percentage		49.00%
Euro​ Infrastructure​ Co Step Acquisition [Member]
Business Acquisition [Line Items]
Percentage of additional interest in subsidiary acquired	51.00%						51.00%
Ownership percentage after completing the acquisition	100.00%						100.00%
The consideration transferred	$ 327,400,000	$ 160,400,000
Payments to acquire business	167,000,000.0
Euro Infrastructure Co.’s cash on hand	121,700,000
Net cash outlay after acquiree's cash on hand	$ 51,000,000.0
Contingent consideration arrangements	the Company may pay or receive up to €20.0 million, or approximately $23.4 million, in cash.				up to plus or minus €20.0 million
Euro​ Infrastructure​ Co Step Acquisition [Member] | Maximum [Member]
Business Acquisition [Line Items]
Amount of estimated purchase price consideration to be settled among the parties over the next 24 months from the closing date	$ 23,400,000						€ 20.0
RigNet, Inc [Member]
Business Acquisition [Line Items]
The consideration transferred	317,900,000
Shares issued in connection with acquisition of business	$ 207,200,000
Shares issued in connection with acquisition of business, net of issuance costs, shares | shares	4.0
Pay down of outstanding borrowings of acquiree	$ 107,300,000
Remaining amount payable			0		$ 0
Total revenues			45,200,000		79,200,000
Net losses			9,900,000		16,200,000
RigNet, Inc [Member] | Selling General and Administrative Expenses [Member]
Business Acquisition [Line Items]
Merger-related transaction costs			$ 7,100,000		$ 7,100,000
RigNet, Inc [Member] | Maximum [Member]
Business Acquisition [Line Items]
Contingent consideration liability	$ 13,800,000