Common Stock (Details)	6 Months Ended			6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013 Common Stock	Dec. 31, 2012 Common Stock	Jun. 30, 2013 Common Class A	Jun. 30, 2013 Common Class B	Dec. 31, 2012 Common Class B	Jun. 30, 2013 Common Class C	Dec. 31, 2012 Common Class C	Jun. 30, 2013 Common Class D	Dec. 31, 2012 Common Class D	Jun. 30, 2013 Common Class E	Dec. 31, 2012 Common Class E	Jun. 30, 2013 Common Class F	Dec. 31, 2012 Common Class F	Jun. 30, 2013 Common Class G	Dec. 31, 2012 Common Class G
Common stock rollforward
Shares outstanding at January 1, 2013		1,423,056	1,420,034	67,991	357,882	357,882	209,882	209,882	279,999	279,999	504,276	504,276	1	1	3	3
Restricted stock issuances	7,251			7,251
Restricted stock repurchased	(769)			(769)
Restricted stock forfeitures	(3,460)			(3,460)
Shares outstanding at June 30, 2013		1,423,056	1,420,034	71,013	357,882	357,882	209,882	209,882	279,999	279,999	504,276	504,276	1	1	3	3