Summary of Significant Accounting Policies Recent Accounting Pronouncements (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		$ 8,000,000
Accounting Standards Update 2017-05 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	$ 30,900,000
Salaries expense [Member] | Accounting Standards Update 2016-02 [Member] [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	10,400,000	10,500,000
Legal expense [Member] | Accounting Standards Update 2016-02 [Member] [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	$ 1,200,000	$ 700,000