Selected Financial Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Mar. 31, 2016		Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2016		Mar. 31, 2015		Mar. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 184,174		$ 218,191		$ 271,923		$ 304,774		$ 324,762		$ 387,554		$ 397,524		$ 385,677		$ 979,062		$ 1,495,517		$ 1,435,103
Operating income (loss)	(56,569)	[1]	(9,400)	[1]	(17,644)	[1]	14,089	[1]	25,672	[1]	(213,580)	[1]	84,723	[1]	66,004	[1]	(69,524)		(37,181)		201,541
Net earnings (loss) attributable to Tidewater Inc.	$ (81,787)		$ (19,509)		$ (43,835)		$ (15,052)		$ (9,076)		$ (160,694)		$ 60,907		$ 43,673		$ (160,183)		$ (65,190)		$ 140,255
Earnings (loss) per share, basic	$ (1.74)		$ (0.42)		$ (0.93)		$ (0.32)		$ (0.19)		$ (3.31)		$ 1.23		$ 0.88		$ (3.41)	[2]	$ (1.34)	[2]	$ 2.84	[2]
Earnings (loss) per share, diluted	$ (1.74)		$ (0.42)		$ (0.93)		$ (0.32)		$ (0.19)		$ (3.31)		$ 1.22		$ 0.88		$ (3.41)	[3]	$ (1.34)	[3]	$ 2.82	[3]

[1] Operating income consists of revenues less operating costs and expenses, depreciation, vessel operating leases, goodwill impairment, general and administrative expenses and gain on asset dispositions, net, of the company’s operations. Goodwill impairment by quarter for fiscal 2016 and 2015 and gain on asset dispositions, net, by quarter for fiscal 2016 and 2015, are as follows:

[2] The company calculates “Loss per share, basic” by dividing “Net loss available to common shareholders” by “Weighted average outstanding share of common stock, basic”.

[3] The company calculates “Loss per share, diluted” by dividing “Net loss available to common shareholders” by “Weighted average common stock and equivalents”.