EPS Calculation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Numerator:
Net income	$ 77,351	$ 84,713
Dividends declared on preferred stock	(2,040)	(2,040)
Dividends, DERs and undistributed earnings allocated to participating securities	(321)	(416)
Net income allocable to common stockholders - basic and diluted	$ 74,990	$ 82,257
Denominator:
Weighted average common shares for basic and diluted earnings per share	358,110,000	356,167,000
Basic and diluted EPS (in dollars per share)	$ 0.21	$ 0.23
Anti-dilutive securities
Anti-dilutive securities excluded from diluted earnings per share calculations (in shares)	1,600,000
Stock options
Anti-dilutive securities
Anti-dilutive securities excluded from diluted earnings per share calculations (in shares)	427,000
Weighted average exercise price (in dollars per share)	$ 10.14
Weighted average remaining contractual life	7 months 6 days
Restricted common stock
Anti-dilutive securities
Anti-dilutive securities excluded from diluted earnings per share calculations (in shares)	447,000
Weighted average grant date fair value (in dollars per share)	$ 7.73
Restricted Stock Units
Anti-dilutive securities
Anti-dilutive securities excluded from diluted earnings per share calculations (in shares)	728,000
Weighted average grant date fair value (in dollars per share)	$ 6.43