Securities Available for Sale (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Summary of temporarily impaired securities
Less Than 12 Months, Fair Value	$ 5,728,844
Less Than 12 Months, Unrealized Loss	(351,699)
12 Months or Longer, Fair Value	0
12 Months or Longer, Unrealized Loss	0
Preferred Stock [Member]
Summary of temporarily impaired securities
Less Than 12 Months, Fair Value	3,944,894
Less Than 12 Months, Unrealized Loss	(82,258)
12 Months or Longer, Fair Value	0
12 Months or Longer, Unrealized Loss	0
Common Stock [Member]
Summary of temporarily impaired securities
Less Than 12 Months, Fair Value	1,783,950
Less Than 12 Months, Unrealized Loss	(269,441)
12 Months or Longer, Fair Value	0
12 Months or Longer, Unrealized Loss	$ 0