Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Dec. 31, 2015	Mar. 31, 2015	Mar. 31, 2014
Reconciliation of the beginning and ending amount of unrecognized tax benefits, excluding interest and penalties
Unrecognized tax benefits, beginning of period	$ 33,784	$ 32,232	$ 25,657
Gross increases—tax positions in prior periods	42,264	21,369	15,412
Gross decreases—tax positions in prior periods	(1,147)	(16,721)	(13,172)
Gross increases—current-period tax positions	5,818	1,469	4,488
Settlements	0	(2,786)	0
Lapse of statute of limitations	(74)	(1,779)	(153)
Unrecognized tax benefits, end of period	$ 80,645	$ 33,784	$ 32,232