Subsequent Events (Details)		1 Months Ended
	Jun. 08, 2017 USD ($) item	Jun. 30, 2017	May 31, 2017 USD ($) item	Mar. 31, 2017 USD ($)	Mar. 31, 2015 USD ($)	Mar. 31, 2014 USD ($)
2015 Debt Facility
Subsequent Events
Minimum interest coverage ratio for following 12 month period (as a percent)				100.00%
Minimum interest coverage ratio for following subsequent year (as a percent)				150.00%
Minimum interest coverage ratio for thereafter (as a percent)				250.00%
Original loan amount					$ 758,000,000
Maximum consolidated net debt to consolidated total capitalization ratio (as a percent)				60.00%
Minimum stockholder's equity balance				$ 400,000,000
Percent of any new equity raised after closing date (as a percent)				50.00%
Percent of positive net income for the immediately preceding financial year (as a percent)				25.00%
Current assets and long-term restricted cash divided by current liabilities ratio (as a percent)				100.00%
2015 Debt Facility | Subsequent events
Subsequent Events
Number of debt principal payments with relaxed covenants | item			2
Minimum cash balance requirement through six months from the Amendment Date			$ 18,000,000
Minimum cash per mortgaged vessel through six months from the Amendment Date			1,000,000
Minimum cash balance requirement from six months from the amendment date through first anniversary			29,000,000
Minimum cash per mortgaged vessel from six months from the Amendment Date through first anniversary			1,600,000
Minimum cash balance requirement from first anniversary through thereafter			40,000,000
Minimum cash per mortgaged vessel from first anniversary through thereafter			2,200,000
Minimum stock offering for recalculation of restricted cash covenants			$ 50,000,000
Percent of principal debt outstanding for recalculation of restricted cash covenants (as a percent)			5.00%
Minimum cash balance required to be maintained if common stock offering met required threshold			$ 20,000,000
Minimum cash per mortgaged vessel if common stock offering met threshold			$ 1,100,000
Minimum interest coverage ratio for following 12 month period (as a percent)			125.00%
Minimum interest coverage ratio for following subsequent year (as a percent)			150.00%
Minimum interest coverage ratio for thereafter (as a percent)			250.00%
Minimum fair market value of mortgaged ships plus any additional security over the outstanding loan balance through March 31, 2018			125.00%
Minimum fair market value of mortgaged ships plus any additional security over the outstanding loan balance from April 1, 2018 through March 31, 2019			130.00%
Minimum fair market value of mortgaged ships plus any additional security over the outstanding loan balance thereafter			135.00%
Amendment fees			$ 1,100,000
The amount of restricted cash released			$ 26,800,000
2017 Bridge Loan | Subsequent events
Subsequent Events
Minimum interest coverage ratio for following 12 month period (as a percent)	125.00%
Minimum interest coverage ratio for thereafter (as a percent)	150.00%
Original loan amount	$ 97,000,000
The amount of restricted cash released	$ 6,000,000
Number of VLGC secured by loan agreement | item	4
Minimum consolidated liquidity	$ 50,000,000
Minimum cash and cash equivalents, including restricted cash freely available and unencumbered basis	$ 10,000,000
Maximum consolidated net debt to consolidated total capitalization ratio (as a percent)	0.60%
Minimum stockholder's equity balance	$ 400,000,000
Percent of any new equity raised after closing date (as a percent)	50.00%
Percent of positive net income for the immediately preceding financial year (as a percent)	25.00%
Current assets and long-term restricted cash divided by current liabilities ratio (as a percent)	100.00%
Minimum aggregate market value to principal amount outstanding ratio (as a percent)	150.00%
2017 Bridge Loan | June 8, 2018 until Maturity Date | Subsequent events
Subsequent Events
Stated rate (as a percent)	8.50%
2017 Bridge Loan | LIBOR | Period Ending December 7, 2017 | Subsequent events
Subsequent Events
Margin added to LIBOR for interest rate on loan facility (as a percent)	2.50%
2017 Bridge Loan | LIBOR | December 8, 2017 until March 7, 2018 | Subsequent events
Subsequent Events
Margin added to LIBOR for interest rate on loan facility (as a percent)	4.50%
2017 Bridge Loan | LIBOR | March 8, 2018 until June 7, 2018 | Subsequent events
Subsequent Events
Margin added to LIBOR for interest rate on loan facility (as a percent)	6.50%
Royal Bank of Scotland plc (RBS)
Subsequent Events
Original loan amount						$ 135,224,500
Debt redemption price (as a percent)		96.00%
Royal Bank of Scotland plc (RBS) | Subsequent events
Subsequent Events
Debt redemption price (as a percent)	96.00%