Junior Subordinated Debentures (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Average Term of Junior Subordinated Debentures	30 years
Interest Expense, Junior Subordinated Debentures	$ 19,600,000
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust [Abstract]
Amount	245,294,000	245,290,000
Junior Subordinated Debt
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust [Abstract]
Rate, weighted average	2.47%
Amount	245,294,000
Junior Subordinated Debt | Sterling Capital Trust IX
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust [Abstract]
Rate	1.76%
Amount	46,392,000
Junior Subordinated Debt | Sterling Capital Trust VIII
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust [Abstract]
Rate	1.94%
Amount	51,547,000
Junior Subordinated Debt | Sterling Capital Trust VII
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust [Abstract]
Rate	1.83%
Amount	56,702,000
Junior Subordinated Debt | Lynnwood Capital Trust II
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust [Abstract]
Rate	2.11%
Amount	10,310,000
Junior Subordinated Debt | Sterling Capital Trust VI
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust [Abstract]
Rate	3.51%
Amount	10,310,000
Junior Subordinated Debt | Sterling Capital Statutory Trust V
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust [Abstract]
Rate	3.56%
Amount	20,619,000
Junior Subordinated Debt | Sterling Capital Trust IV
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust [Abstract]
Rate	3.46%
Amount	10,310,000
Junior Subordinated Debt | Sterling Capital Trust III
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust [Abstract]
Rate	3.56%
Amount	14,433,000
Junior Subordinated Debt | Lynnwood Capital Trust I
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust [Abstract]
Rate	3.46%
Amount	9,437,000
Junior Subordinated Debt | Klamath First Capital Trust I
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust [Abstract]
Rate	4.48%
Amount	$ 15,234,000