Goodwill (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Goodwill And Intangible Assets Disclosure [Abstract]
Impairment loss for goodwill	$ 0	$ 0	$ 0	$ 0
Accumulated impairment of goodwill since the Merger	$ 4,766,190,000		$ 4,766,190,000