Share Capital - Options (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Summary of stock option plans:
Options exercised during the year		802	480
Summary of stock options and related activity:
Options exercised during the year		(802)	(480)
Stock options
Summary of stock option plans:
Options granted to purchase ordinary shares under directors and employees incentive compensation plans (shares)		2,200	1,974	1,025
Weighted average grant date fair value (per share)		$ 5.99	$ 6.51	$ 8.60
Total intrinsic value of stock options exercised		$ 19,471	$ 8,546	$ 7,499
Options exercised during the year		810	480	424
Compensation expense related to stock option plans		$ 11,065	$ 8,961	$ 9,961
Estimated tax benefit related to stock option plans		$ 355	$ 0	$ (2)
Summary of stock options and related activity:
Outstanding at beginning of year, shares		10,749
Granted, shares		2,200
Options exercised during the year		(810)	(480)	(424)
Canceled/expired, shares		(278)
Outstanding at end of year, shares		11,861	10,749
Options exercisable, shares		8,002
Options available for grant, shares	[1]	8,355
Outstanding at beginning of year, weighted average exercise price		$ 28.59
Granted, weighted average exercise price		34.64
Exercised, weighted average exercise price		12.35
Canceled/expired, weighted average exercise price		60.83
Outstanding at end of year, weighted average exercise price		30.07	$ 28.59
Options exercisable, weighted average exercise price		$ 27.75
Weighted average remaining contractual term		5 years 6 months	5 years 4 months 24 days
Weighted average remaining contractual term, options exercisable		4 years
Aggregate intrinsic value, beginning of year		$ 121,085
Aggregate intrinsic value, end of year		86,558	$ 121,085
Aggregate intrinsic value, options exercisable		77,366
Total unrecognized stock based compensation expense		$ 15,300
Number of non-vested options outstanding		3,900
Period for recognition of unrecognized expense		1 year 3 months 18 days

[1] Available for grant includes shares that may be granted as either stock options, restricted stock, restricted stock units or performance units.