Annual report pursuant to Section 13 and 15(d)

Shareholders' Equity (Narrative) (Details)

v3.6.0.2
Shareholders' Equity (Narrative) (Details) - USD ($)
1 Months Ended 12 Months Ended
Feb. 10, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Class of Stock [Line Items]        
Stock repurchase plan, authorized amount   $ 700,000,000    
Aggregate shares repurchased under stock repurchase plan   20,992,940    
Stock repurchased to date, value   $ 526,522,000    
Stock Repurchased During Period, Value   $ 11,000 $ 70,068,000 $ 15,000,000
Share Repurchase Program [Domain]        
Class of Stock [Line Items]        
Aggregate shares repurchased under stock repurchase plan 616,152      
Stock Repurchased During Period, Value $ 33,000,000