Investment Securities (Details 2) - USD ($)	3 Months Ended	6 Months Ended
Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Held-to-maturity debt securities amortized cost disclosures
Due after one year through five years, held-to-maturity debt securities amortized cost	$ 2,400,000		$ 2,400,000
Amortized cost, held-to-maturity debt securities	2,400,000		2,400,000		$ 2,400,000
Held-to-maturity debt securities, Estimated fair value disclosures
Due after one year through five years, held-to-maturity debt securities, Estimated fair value	2,400,000		2,400,000
Estimated Fair Value	2,400,000		2,400,000		2,400,000
Available-for-sale debt securities amortized cost disclosures
Due after five years through ten years, available-for-sale debt securities amortized cost	749,000		749,000
Due after ten years, available-for-sale debt securities amortized cost	268,461,000		268,461,000
Residential mortgage-backed securities, amortized cost	4,363,026,000		4,363,026,000
Equity securities, amortized cost	28,075,000		28,075,000
Amortized cost, Available for sale securities	4,660,311,000		4,660,311,000		4,894,428,000
Available for sale debt securities, Estimated Fair Value Disclosures
Due after five years through ten years, available-for-sale debt securities, Estimated Fair Value	823,000		823,000
Due after ten years, available-for-sale debt securities, Estimated Fair Value	278,473,000		278,473,000
Residential mortgage-backed securities, Estimated Fair Value	4,365,066,000		4,365,066,000
Equity securities, Estimated Fair Value	29,110,000		29,110,000
Estimated fair value, Available for sale securities	4,673,472,000		4,673,472,000		$ 4,911,963,000
Amortized cost of available for sale investment securities pledged	2,077,210,000		2,077,210,000
Fair value of available for sale investment securities pledged	2,083,921,000		2,083,921,000
Proceeds from sales and calls of available for sale securities	23,992,000	$ 110,020,000	30,282,000	$ 368,296,000
Proceeds from sales of mortgage-backed securities	23,992,000	110,020,000	23,992,000	367,641,000
Gross gains realized on sales	0	1,371,000	1,000	9,479,000
Gross losses realized on sales	427,000	1,750,000	428,000	1,750,000
Impairment charges on available-for-sale investment securities	$ 224,000	$ 189,000	$ 451,000	$ 279,000

The amortized cost of available-for-sale securities that serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee does not have the right by contract or custom to sell or re-pledge them to an unrelated party.

No definition available.