Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Mar. 31, 2017
Property, Plant and Equipment, Net [Abstract]
Property and equipment, accumulated depreciation	$ 852,892	$ 821,276
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)	$ 0.01210544422	$ 0.01004128322
Common stock, authorized shares	175,000,000	175,000,000
Common stock, issued shares	46,508,000	46,508,000
Treasury stock, shares	0	0