Income Taxes - Narrative (Details) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
US tax on deemed repatriated foreign earnings		$ 59,114,000	$ 57,138,000	$ 0	$ 0
Transition tax related to repatriation of foreign earnings payable in next twelve months	$ 4,571,000		4,571,000
Re-measurement of deferred taxes			14,395,000	0	0
Intercompany dividends			250,000,000	13,692,000	0
Adjustments to transition tax for accumulated foreign earnings	(3,887,000)
Adjustments to deferred taxes due to change in tax rate	973,000
Foreign income before taxes			149,214,000	63,011,000	105,938,000
Expected future taxable income to fully realize the deferred tax assets			118,118,000
Change in net deferred tax assets attributable to other comprehensive income			253,000
Domestic taxable income			321,482,000	(56,305,000)	50,947,000
Valuation allowance	0		0	0
Unremitted earnings of non-US subsidiaries	385,884,000	627,787,000	385,884,000
Distribution from foreign subsidiary	250,000,000
Provision for income tax			106,302,000	(12,696,000)	34,620,000
Non US subsidiary cash and cash equivalents	203,032,000		203,032,000
Unremitted earnings of non-US subsidiaries not subject to transition tax	15,389,000		15,389,000
Unrecognized tax benefits	9,594,000		9,594,000	11,727,000	8,695,000
Unrecognized tax benefits and associated interest and penalties	3,224,000		3,224,000	2,990,000
Unrecognized tax benefits			1,301,000	$ 2,691,000	$ 3,670,000
Unrecognized tax benefits income tax penalties and interest Expense			369,000
Unrecognized tax benefit expected to settle in next twelve months	0		0
US Federal Tax Authority
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
US tax on deemed repatriated foreign earnings			57,138,000
State Tax Authority
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
US tax on deemed repatriated foreign earnings			1,976,000
Transition tax on dividend remitted from foreign subsidiary			607,000
Adjustments to transition tax for accumulated foreign earnings	1,558,000
State transition tax expense on foreign earnings		$ 927,000
Provision for income tax	607,000
Periods Before Fiscal Year 2018
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
US tax on deemed repatriated foreign earnings			$ 44,871,000
Adjustments to transition tax for accumulated foreign earnings	(7,570,000)
2018
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Adjustments to transition tax for accumulated foreign earnings	$ 3,683,000