Stock-Based Compensation Plans (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended			3 Months Ended		9 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Stock-Based Compensation Plans
Unrecognized compensation cost	$ 10.6			$ 10.6		$ 10.6
Weighted average life over which unrecognized compensation is expected to be recognized						1 year 7 months 24 days
General and administrative expenses
Stock-Based Compensation Plans
Stock-based compensation expense				$ 1.2	$ 1.3	$ 3.2	$ 3.1
Restricted stock awards
Number of Shares
Unvested at the beginning of the period (in shares)						929,000
Granted (in shares)			250,000			277,514
Vested (in shares)						(90,014)
Forfeited (in shares)						(1,875)
Unvested at the end of the period (in shares)	1,114,625			1,114,625		1,114,625
Weighted-Average Grant-Date Fair Value
Unvested at the beginning of the period (in dollars per share)						$ 19.70
Granted (in dollars per share)						7.75
Vested (in dollars per share)						7.60
Forfeited (in dollars per share)						7.82
Unvested at the end of the period (in dollars per share)	$ 17.72			$ 17.72		$ 17.72
Restricted stock awards | Vest immediately
Stock-Based Compensation Plans
Vesting (as a percent)			25.00%
Restricted stock awards | Vest one year after grant
Stock-Based Compensation Plans
Vesting (as a percent)			25.00%
Restricted stock awards | Vest two years after grant
Stock-Based Compensation Plans
Vesting (as a percent)			25.00%
Restricted stock awards | Vest three years after grant
Stock-Based Compensation Plans
Vesting (as a percent)			25.00%
Non-executive director | Restricted stock awards
Number of Shares
Granted (in shares)	8,695	10,130	6,950
Non-employee consultant | Restricted stock awards
Number of Shares
Granted (in shares)	1,739