Revenue Recognition (Revenue disaggregated by timing of revenue recognition) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Revenue From Contract With Customer [Abstract]
Revenues Recognized Over Time	$ 757,736	$ 706,072
Revenues recognized at a point in time	90,190	89,138
Total revenues recognized under ASC 606	847,926	795,210
Revenues recognized under ASC 840	95,857	83,452
Revenues recognized under ASC 944	51,189	52,046
Revenues recognized under ASC 320	24,605	27,217
Total revenues	$ 1,019,577	$ 957,925