Regulatory Capital (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012
Sterling [Member]
Tier One Leverage Capital [Abstract]
Tier One Leverage Capital	$ 1,108,550
Tier One Leverage Capital to Average Assets	12.20%
Tier One Leverage Capital Required for Capital Adequacy	364,954
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%
Tier One Leverage Capital Required to be Well Capitalized	456,193
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%
Tier One Risk Based Capital [Abstract]
Tier One Risk Based Capital	1,108,550
Tier One Risk Based Capital to Risk Weighted Assets	17.30%
Tier One Risk Based Capital Required for Capital Adequacy	256,048
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.00%
Tier One Risk Based Capital Required to be Well Capitalized	384,072
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	6.00%
Capital [Abstract]
Capital	1,189,629
Capital to Risk Weighted Assets	18.60%
Capital Required for Capital Adequacy	512,096
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%
Capital Required to be Well Capitalized	640,120
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%
Sterling Bank [Member]
Tier One Leverage Capital [Abstract]
Tier One Leverage Capital	1,097,834
Tier One Leverage Capital to Average Assets	12.00%
Tier One Leverage Capital Required for Capital Adequacy	366,232
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%
Tier One Leverage Capital Required to be Well Capitalized	457,790
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%
Tier One Risk Based Capital [Abstract]
Tier One Risk Based Capital	1,097,834
Tier One Risk Based Capital to Risk Weighted Assets	17.10%
Tier One Risk Based Capital Required for Capital Adequacy	256,286
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.00%
Tier One Risk Based Capital Required to be Well Capitalized	384,428
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	6.00%
Capital [Abstract]
Capital	1,178,986
Capital to Risk Weighted Assets	18.40%
Capital Required for Capital Adequacy	512,571
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%
Capital Required to be Well Capitalized	$ 640,714
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%