Equity - Additional Information (Details) - USD ($) $ in Millions			3 Months Ended
		Apr. 19, 2018	Mar. 31, 2018	Mar. 31, 2017
Dividends Payable [Line Items]
Dividend paid	[1]		$ 22.3	$ 22.1
Shares repurchased under repurchase program (in shares)			0
Stock repurchase program, remaining authorized repurchase amount			$ 238.8
Subsequent Event
Dividends Payable [Line Items]
Dividend paid		$ 22.3

[1] See Note 14 regarding quarterly cash dividend.