Stock-based Compensation - 2011 Management Equity Plan - Narrative (Details) (USD $)	0 Months Ended		9 Months Ended
	Jan. 16, 2014	Dec. 30, 2011	Jan. 31, 2014	Jan. 31, 2013	Jan. 14, 2014	Apr. 30, 2013	Apr. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost not yet recognized			$ 27,100,000
Conversion Transaction One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost not yet recognized	2,000,000
Compensation cost not yet recognized, period for recognition	2 years 6 months
Conversion Transaction Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost not yet recognized	500,000
Compensation cost not yet recognized, period for recognition	10 years
2011 Management Equity Plan | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option term			10 years
Grant exercise price, as a percentage of fair value			100.00%
Weighted average exercise price		26.06
2011 Management Equity Plan | Time and performance options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years
Vesting rights, percentage			25.00%
Vesting period, from date of grant			1 year
Exchange of options, options exchanged			909,124
Weighted average exercise price			$ 26.06		$ 26.06	$ 26.06	$ 26.06
Compensation cost not yet recognized			2,100,000
Compensation cost not yet recognized, period for recognition			2 years
Weighted average fair value, per share	$ 0.26
Compensation expense			5,300,000	0
2011 Management Equity Plan | Time and performance options | Conversion Transaction One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exchange of options, options exchanged	183,219
2011 Management Equity Plan | Time and performance options | Conversion Transaction Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exchange of options, options exchanged	725,905
2011 Management Equity Plan | Performance stock option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exchange of options, options exchanged			1,716,230
Exchange of options, shares issued		170,000
Weighted average exercise price			$ 0.00		$ 26.06	$ 26.06	$ 26.06
Weighted average fair value, per share	$ 0.13
Compensation expense			$ 13,900,000	$ 0
2011 Management Equity Plan | Performance stock option | Conversion Transaction One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exchange of options, options exchanged	390,473
2011 Management Equity Plan | Performance stock option | Conversion Transaction Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exchange of options, options exchanged	1,325,757
2013 Omnibus Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average exercise price			$ 10.00
2013 Omnibus Incentive Plan | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Vesting rights, percentage	33.30%
Vesting period, from date of grant	1 year
2013 Omnibus Incentive Plan | Service vesting options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average exercise price	$ 0.0001
2013 Omnibus Incentive Plan | Service vesting options | Conversion Transaction One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exchange of options, shares issued	46,403
2013 Omnibus Incentive Plan | Share price performance options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average exercise price	$ 10.00		$ 10.00
2013 Omnibus Incentive Plan | Share price performance options | Conversion Transaction One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exchange of options, shares issued	193,891
2013 Omnibus Incentive Plan | Service vesting shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average exercise price	$ 0
2013 Omnibus Incentive Plan | Service vesting shares | Conversion Transaction Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exchange of options, shares issued	252,976
2013 Omnibus Incentive Plan | Share price performance shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average exercise price	$ 0
2013 Omnibus Incentive Plan | Share price performance shares | Conversion Transaction Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exchange of options, shares issued	669,228