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Subsidiary Guarantors - Schedule of Consolidating Statement of Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	2 Months Ended	3 Months Ended														8 Months Ended		12 Months Ended
	Dec. 31, 2014	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Dec. 31, 2014	Apr. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Apr. 30, 2014	Apr. 30, 2013
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	$ (6,017)	$ (7,020)	$ 2,259	$ 943	$ (7,963)	$ 361	$ (154)	$ (15,633)	$ (11,033)	$ (575)	$ (163)	$ (13,518)	$ (11,474)	$ (21,092)	$ (8,379)	$ (5,810)		$ (11,781)		$ (27,404)	$ (54,463)
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) resulting from changes in fair value of derivative instruments																				(36)	(2,910)
Realized loss (gain) on derivative instruments reclassified into earnings																				655	4,247
Unrealized gain (loss) resulting from changes in fair value of marketable securities																19		(51)		12	23
Other comprehensive income (loss), net of tax																19	$ 631	(51)	$ 19	631	1,360
Comprehensive income (loss)																(5,791)		(11,832)		(26,773)	(53,103)
Less: Comprehensive income (loss) attributable to noncontrolling interests																208		1,188		(4,309)	(321)
Comprehensive income (loss) attributable to common stockholders																(5,999)		(13,020)		(22,464)	(52,782)
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)																(6,018)		(12,969)		(23,095)	(54,142)
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) resulting from changes in fair value of derivative instruments																					(1,257)
Realized loss (gain) on derivative instruments reclassified into earnings																					3,626
Other comprehensive income (loss), net of tax																					2,369
Comprehensive income (loss)																(6,018)		(12,969)		(23,095)	(51,773)
Comprehensive income (loss) attributable to common stockholders																(6,018)		(12,969)		(23,095)	(51,773)
Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)																25,926		33,371		23,807	(19,954)
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) resulting from changes in fair value of marketable securities																19		(51)		12	23
Other comprehensive income (loss), net of tax																19		(51)		12	23
Comprehensive income (loss)																25,945		33,320		23,819	(19,931)
Comprehensive income (loss) attributable to common stockholders																25,945		33,320		23,819	(19,931)
Non-Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)																430		2,427		(9,305)	(5,090)
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) resulting from changes in fair value of derivative instruments																				(36)	(1,653)
Realized loss (gain) on derivative instruments reclassified into earnings																				655	621
Other comprehensive income (loss), net of tax																				619	(1,032)
Comprehensive income (loss)																430		2,427		(8,686)	(6,122)
Less: Comprehensive income (loss) attributable to noncontrolling interests																208		1,188		(4,309)	(321)
Comprehensive income (loss) attributable to common stockholders																222		1,239		(4,377)	(5,801)
Elimination [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)																(26,148)		(34,610)		(18,811)	24,723
Other comprehensive income (loss), net of tax:
Comprehensive income (loss)																(26,148)		(34,610)		(18,811)	24,723
Comprehensive income (loss) attributable to common stockholders																$ (26,148)		$ (34,610)		$ (18,811)	$ 24,723