Debt and Borrowing Arrangements (Details 5) (USD $) In Millions, unless otherwise specified	0 Months Ended		0 Months Ended				6 Months Ended
	Jun. 13, 2013 Chesapeake Series 2013-1 term notes	Jun. 30, 2013 Committed Facilities	May 22, 2013 Committed Facilities Credit Suisse First Boston Mortgage Capital LLC	Jun. 21, 2013 Committed Facilities The Royal Bank of Scotland plc	Jun. 21, 2013 Uncommitted warehouse facilities The Royal Bank of Scotland plc	Jun. 30, 2013 4.0% Convertible notes due 2014	Jun. 30, 2013 6.0% Convertible Notes due 2017
Debt and Borrowing Arrangements
Debt issued	$ 700
Principal amount of notes						250	250
Borrowing capacity		3,155	675	250	250
Rolling term			364 days
Interest rate (as a percent)						4.00%	6.00%
Amount by which the if-converted value exceeded its principle amount							$ 148