Regulatory Capital (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Tier One Leverage Capital [Abstract]
Tier One Leverage Capital	$ 1,115,834	$ 1,045,761
Tier One Leverage Capital to Average Assets	12.10%	11.40%
Tier One Leverage Capital Required for Capital Adequacy	367,909	366,048
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage Capital Required to be Well Capitalized	459,886	457,560
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%
Tier One Risk Based Capital [Abstract]
Tier One Risk Based Capital	1,115,834	1,045,761
Tier One Risk Based Capital to Risk Weighted Assets	17.50%	17.80%
Tier One Risk Based Capital Required for Capital Adequacy	255,750	234,859
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.00%	4.00%
Tier One Risk Based Capital Required to be Well Capitalized	383,625	352,288
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	6.00%	6.00%
Capital [Abstract]
Capital	1,196,773	1,120,563
Capital to Risk Weighted Assets	18.70%	19.10%
Capital Required for Capital Adequacy	511,499	469,718
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%	8.00%
Capital Required to be Well Capitalized	639,374	587,147
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%	10.00%
Sterling Bank
Tier One Leverage Capital [Abstract]
Tier One Leverage Capital	1,100,443	1,019,016
Tier One Leverage Capital to Average Assets	12.00%	11.10%
Tier One Leverage Capital Required for Capital Adequacy	368,053	366,018
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage Capital Required to be Well Capitalized	460,066	457,523
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%
Tier One Risk Based Capital [Abstract]
Tier One Risk Based Capital	1,100,443	1,019,016
Tier One Risk Based Capital to Risk Weighted Assets	17.20%	17.40%
Tier One Risk Based Capital Required for Capital Adequacy	255,875	234,468
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.00%	4.00%
Tier One Risk Based Capital Required to be Well Capitalized	383,812	351,705
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	6.00%	6.00%
Capital [Abstract]
Capital	1,181,421	1,093,697
Capital to Risk Weighted Assets	18.50%	18.70%
Capital Required for Capital Adequacy	511,749	468,936
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%	8.00%
Capital Required to be Well Capitalized	$ 639,687	$ 586,171
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%	10.00%