Stockholders' Equity - Stock Appreciation Rights (Details) - 2007 LTIP SARs - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Maximum contractual term of SARs with final vesting date of December 31, 2011 (in years)	10 years
Maximum contractual term of SARs with final vesting date of December 31, 2016 (in years)	15 years
Stock Incentive Plan 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Stock appreciation rights issued	0
Equity Incentive Plans 2006
Number of Shares
Nonvested at the beginning of the period (in shares)	240,000	620,000	715,000
Exercised (in shares)	(240,000)	(290,000)	(80,000)
Forfeited (in shares)			(15,000)
Cancelled (in shares)		(90,000)
Nonvested at the end of the period (in shares)	0	240,000	620,000	715,000
Exercisable at end of period (in shares)	0
Weighted- Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 26.73	$ 26.73	$ 26.73
Exercised (in dollars per share)	26.73	26.73	26.73
Forfeited (in dollars per share)			26.73
Cancelled (in dollars per share)		26.73
Outstanding at the end of the period (in dollars per share)	0.00	$ 26.73	$ 26.73	$ 26.73
Exercisable (in dollars per share)	$ 0.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted- Average Remaining Contractual Term (Years)	0 years	5 years 1 month 6 days	3 years 6 months	5 years 9 months 18 days
Aggregate Intrinsic Value	$ 0	$ 7,920	$ 20,600	$ 33,000
Exercisable (in years)	0 years
Exercisable (in dollars)	$ 0