Stockholders' Equity Stockholders' Equity (Narrative) (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	May 10, 2016	Oct. 31, 2015
2016 Stock Repurchase Program
Class of Stock [Line Items]
Stock repurchase program, authorized amount			$ 50,000,000
Amount available to be repurchased	$ 44,000,000	$ 44,000,000
2013 Stock Repurchase Program
Class of Stock [Line Items]
Stock repurchase program, authorized amount				$ 60,000,000
Shares Outstanding Class A | 2016 Stock Repurchase Program
Class of Stock [Line Items]
Shares repurchased (in shares)	0	0