XML 131 R112.htm IDEA: XBRL DOCUMENT v3.8.0.1
Employee Stock and Incentive Plans - Employee Stock Ownership Plan (Details) - USD ($)
shares in Millions, $ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Employee Stock Ownership Plan [Abstract]      
ESOP Employer Loan In 1990, the ESOP issued a $75.0 million note to use as consideration for 2.8 million shares (1.9 million shares adjusted for stock splits) of our common stock. The note matured in December 2015.    
ESOP Compensation Expense $ 11.0 $ 9.2 $ 9.0
ESOP Shares, Allocated 1.4 1.6 1.8
ESOP Shares, Unallocated 0.0 0.0 0.0
ESOP Shares, Total 1.4 1.6 1.8
ESOP Shares, Fair Value of Unallocated Shares $ 0.0 $ 0.0 $ 0.0