Common Stock - (Narrative) (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015	Jan. 21, 2016
Schedule Of Common Stock [Line Items]
Shares repurchased (shares)	1,671,923	3,894,673
Remaining authorized amount	$ 23.2
Shares outstanding	28,810,883		30,358,509
Common Class A [Member]
Schedule Of Common Stock [Line Items]
Shares outstanding	28,810,883		30,358,509
Restricted issued but not yet vested, shares	830,418		836,031
New Board Authorized Share Repurchase Program
Schedule Of Common Stock [Line Items]
Stock repurchase program, authorized amount				$ 50.0