Debt and Tax Gross-ups on Debt (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended	35 Months Ended									3 Months Ended	0 Months Ended	3 Months Ended	0 Months Ended	1 Months Ended	3 Months Ended					0 Months Ended		3 Months Ended	0 Months Ended			0 Months Ended			0 Months Ended	3 Months Ended		0 Months Ended	3 Months Ended		0 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Sep. 19, 2011 Hexagon warrant exercisable until August 1, 2017	Apr. 25, 2011 Hexagon warrant exercisable until August 1, 2017	Jun. 30, 2013 Very Hungry Notes Embedded derivative	Aug. 01, 2012 AWP	Jun. 30, 2013 Apollo Notes	Mar. 31, 2013 Apollo Notes	Jun. 30, 2013 Karlsson Group	Jun. 30, 2013 Karlsson Group Very Hungry Notes Embedded derivative	Apr. 15, 2013 Karlsson Group Extension Agreement	Jun. 30, 2013 Karlsson Group Extension Agreement	Apr. 15, 2013 Karlsson Group Prospect Global Resources Inc. Extension Agreement	Nov. 30, 2012 Karlsson Group Senior secured promissory note	Jun. 30, 2013 Karlsson Group Senior secured promissory note	Jun. 26, 2013 Karlsson Group Senior secured promissory note item	Apr. 15, 2013 Karlsson Group Senior secured promissory note item	Mar. 31, 2013 Karlsson Group Senior secured promissory note	Aug. 01, 2012 Karlsson Group Senior secured promissory note item	Jul. 01, 2013 Karlsson Group Senior secured promissory note Extension Agreement	Apr. 15, 2013 Karlsson Group Senior secured promissory note Extension Agreement	Jun. 30, 2013 Karlsson Group Senior secured promissory note Extension Agreement	Aug. 01, 2012 Karlsson Group Senior secured promissory note March 30, 2013 Installment Due	Aug. 01, 2012 Karlsson Group Senior secured promissory note July 31, 2013 Installment Due	Jun. 30, 2013 Karlsson Group Senior secured promissory note AWP Extension Agreement	Apr. 15, 2013 Affiliates of Apollo Global Management, LLC Apollo Notes	Mar. 07, 2013 Affiliates of Apollo Global Management, LLC Apollo Notes item	Jun. 30, 2013 Affiliates of Apollo Global Management, LLC Apollo Notes	Apr. 15, 2013 Affiliates of Apollo Global Management, LLC Apollo Notes Extension Agreement	Jun. 30, 2013 Very Hungry and the Scott Reiman 1991 Trust	May 02, 2013 Very Hungry and the Scott Reiman 1991 Trust Hexagon warrant exercisable until August 1, 2017	May 02, 2013 Very Hungry and the Scott Reiman 1991 Trust Very Hungry Notes	Jun. 30, 2013 Very Hungry and the Scott Reiman 1991 Trust Very Hungry Notes	Jun. 30, 2013 Very Hungry and the Scott Reiman 1991 Trust Very Hungry Notes Embedded derivative	Jul. 10, 2013 Very Hungry and the Scott Reiman 1991 Trust Very Hungry Notes Subsequent Events
Debt
Total debt and tax gross-ups	$ 111,832,000	$ 111,832,000	$ 128,258,000					$ 6,750,000	$ 6,750,000							$ 115,282,000			$ 115,282,000		$ 117,500,000													$ 5,500,000
Tax gross-up																17,629,000			6,226,000
Less: Unamortized debt discount	(33,329,000)	(33,329,000)									(2,900,000)					(34,528,000)																		(2,215,000)
Less: current portion of debt and tax gross-ups	(4,063,000)	(4,063,000)	(128,258,000)
Total long-term debt and tax gross-ups	107,769,000	107,769,000
Amortization of debt discount	3,800,000	3,800,000									1,499,000					3,801,000																		1,014,000
Face value																				125,000,000
Interest rate (as a percent)																				9.00%		9.00%							11.00%				0.00%
Principal payments made															9,700,000
Principal payments payable expressed as percentage of net proceeds															40.00%												33.00%
Number of installments in which principal amount is payable																				2
Periodic principal payment (in dollars)																								40,300,000	75,000,000
Term of debt instrument from completion of Definitive Feasibility Study																						12 months
Increase in principal balance																					2,200,000
Principal payments payable expressed as a percentage of gross proceeds																						10.00%					10.00%			10.00%
Amount borrowed																																	5,000,000
Amount of unsecured subordinated promissory notes exchanged																												6,800,000					5,500,000
Exercise price (in dollars per share)				$ 0.30	$ 0.30																											$ 0.30	$ 0.30
Realized derivative gain related to the embedded conversion options	2,900,000	(53,766,000)																													2,900,000
Estimated fair value of the embedded conversion options						2,900,000
Offering price per share (in dollars per share)																																			$ 0.22
Number of senior mandatorily convertible preferred stock shares issued for exchange of unsecured subordinated promissory notes																																				5.5
Period for mandatory pre-payment of debt																							5 days
Minimum ownership percentage to avoid pre-payment							50.00%																			50.00%
Percentage of membership interests pledged for debt														100.00%
Note payable including tax gross-up, accrued interest and the remaining unpaid principal balance																							142,700,000
Note payable including tax gross-up, accrued interest and the remaining unpaid principal balance, Current										142,700,000													1,200,000
Additional tax gross-ups																							2,300,000
Tax gross-up accrued	1,164,000	1,164,000	6,226,000							1,200,000													1,200,000
Number of promissory notes issued																												2
Gain on Debt Restructuring
Number of restructurings																	2	2
Percentage of gross revenue												1.00%	2.00%			1.00%
Additional consideration 1% gross revenue interest																9,200,000
Additional Consideration tax gross-ups																11,403,000
Additional consideration-warrants																412,000
Fees paid to the Karlsson Group																400,000
Reduction in the fair value of the amended Karlsson Note																(34,529,000)
Net gain on debt extinguishment	$ 13,114,000	$ 13,114,000														$ (13,114,000)