Stockholders' Equity, Stock Repurchase Program (Details) - $ / shares	3 Months Ended		207 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Aug. 04, 2015
Stock Repurchase Program [Abstract]
Incremental Class A shares authorized to buyback (in shares)				500,000
Shares repurchased (in shares)	30,503	41,393	9,583,156
Average price per share of repurchased shares (in dollars per share)	$ 29.42	$ 77.19	$ 44.76
Share available under program to repurchase (in shares)	551,652		551,652