Summary of Significant Accounting Policies - Property and Equipment and Goodwill (Details)	12 Months Ended
	Dec. 31, 2016 item
Goodwill.
Number of reporting units to which Goodwill has been allocated	2
Building and improvements | Minimum
Goodwill.
Property, Plant and Equipment, Useful Life	30 years
Building and improvements | Maximum
Goodwill.
Property, Plant and Equipment, Useful Life	50 years
Leasehold improvements | Minimum
Goodwill.
Property, Plant and Equipment, Useful Life	5 years
Leasehold improvements | Maximum
Goodwill.
Property, Plant and Equipment, Useful Life	20 years
Furniture, fixtures and other equipment | Minimum
Goodwill.
Property, Plant and Equipment, Useful Life	4 years
Furniture, fixtures and other equipment | Maximum
Goodwill.
Property, Plant and Equipment, Useful Life	10 years