Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2013	Mar. 31, 2013
Condensed Consolidated Balance Sheets
Property and equipment, accumulated depreciation	$ 785,335	$ 771,398
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	1,431,000	1,519,000