Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2018
Income Tax Disclosure [Line Items]
Effective income tax rate	31.00%	33.00%	18.00%	30.00%
U.S. federal statutory income tax rate			21.00%		31.50%
Measurement period taxes			1 year
Income taxes	$ 15,365	$ 13,898	$ 9,966	$ 13,435
Tax benefit - excluding dividend tax reversal [Member]
Income Tax Disclosure [Line Items]
Effective income tax rate	33.00%		32.00%
Prior to Tax Cuts and Jobs Act [Member]
Income Tax Disclosure [Line Items]
U.S. federal statutory income tax rate			35.00%
Subsequent to Tax Cuts and Jobs Act [Member]
Income Tax Disclosure [Line Items]
U.S. federal statutory income tax rate			21.00%