Shareholders' Equity - Additional Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($) Director shares	Mar. 31, 2016 shares
Capital stock [Abstract]
Number of directors entitled to be elected, minimum | Director	3
Percentage of directors entitled to be elected, maximum	33.33%
Incentive Plans [Abstract]
LTI Plan expiration date	Feb. 28, 2025
Shares available for future stock compensation grants (in million shares)	6,400,000
Grants in period, stock options (in shares)		500,000
Grants in period, restricted share awards (in shares)	400,000	400,000
Share Repurchase Program [Abstract]
Repurchase of class A common shares (in shares)	0	0
Authorized amount | $	$ 1,512.5
Common Class A [Member]
Capital stock [Abstract]
Shares reserved for issuance of stock	8,000,000