Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Mar. 31, 2014
Statement of Financial Position [Abstract]
Property and equipment, accumulated depreciation	$ 811,576	$ 805,687
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, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized shares	175,000,000	175,000,000
Common stock, issued shares	46,508,000	46,508,000
Treasury stock, shares	1,384,000	1,519,000