Reportable Operating Segments - Reconciliation (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Mar. 31, 2016
Reconciliations of total assets from reportable segments to the condensed consolidated balance sheets
Cash and cash equivalents	$ 230,586	$ 291,764	$ 110,047	$ 245,956
Deferred tax assets	52,470	44,708
Total assets	1,520,288	1,191,780
Reportable segments
Reconciliations of total assets from reportable segments to the condensed consolidated balance sheets
Total assets	1,010,987	606,058
Unallocated to Segments
Reconciliations of total assets from reportable segments to the condensed consolidated balance sheets
Cash and cash equivalents	230,586	291,764
Deferred tax assets	52,470	44,708
Other unallocated corporate assets	$ 226,245	$ 249,250