Shareholders' Equity - Narrative (Details)	1 Months Ended	3 Months Ended		9 Months Ended
	Mar. 31, 2017 USD ($) shares	Dec. 31, 2017 $ / shares	Dec. 31, 2016 $ / shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2017 SFr / shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2016 SFr / shares	Mar. 31, 2014 USD ($)
Stockholders' Equity Note [Abstract]
Authorized amount in buyback program	$ 250,000,000.0							$ 250,000,000.0
Shares authorized to be repurchased (in shares) | shares	17,300,000.0
Period to complete share repurchase program	3 years
Repurchase of shares (in shares) | shares				600,000		3,300,000
Purchases of registered shares				$ 20,408,000		$ 63,764,000
Cash dividend declared per share (in dollars per share) | (per share)				$ 0.63	SFr 0.61	$ 0.57	SFr 0.56
Cash dividend paid per share (in dollars per share) | (per share)		$ 0.00	$ 0.00	$ 0.63	SFr 0.61	$ 0.57	SFr 0.56
Dividends paid				$ (104,200,000)		$ (93,100,000)