Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Mar. 31, 2018
Statement of Financial Position [Abstract]
Accrued expenses (1)	$ 96,666	$ 125,119
Property, Plant and Equipment, Net [Abstract]
Property and equipment, accumulated depreciation	$ 857,866	$ 866,614
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, authorized shares	10,000,000	10,000,000
Preferred stock, issued shares	0	0
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Common stock, par value (in dollars per share)	$ 0.009993755296	$ 0.009992761427
Common stock, authorized shares	175,000,000	175,000,000
Common stock, issued shares	57,435,867	56,641,000