Employee Benefit Plans (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 person	Dec. 31, 2011	Dec. 31, 2010	Mar. 14, 2012
Employee Benefit Plans
Maximum contribution by employee (as a percent)	50.00%
Percentage of employer contribution of first 6 percent of covered compensation	50.00%
Maximum employee contribution matched by employer as a percentage of covered compensation	6.00%
Profit sharing and matching contribution expense	$ 20.4	$ 17.6	$ 13.0
Percentage of incentive compensation	100.00%
Net deferred compensation expense	0.7	0.9	1.0
Supplemental Executive Retirement Plan ("SERP")
Supplemental Executive Retirement Plan ("SERP"):
Number of executives (in persons)	1
Number of units converted into the deferred compensation stock fund				167,423
Deferred compensation stock fund in equity				8.3
Pension expense from conversion of fully vested interest into the deferred compensation stock fund in equity	1.7
Pension expense	1.9	0.9	0.8
Unfunded pension liability				8.3
Supplemental Executive Retirement Plan ("SERP") for former executives of the Pacific Bank
Supplemental Executive Retirement Plan ("SERP"):
Number of executives (in persons)	3
Pension expense	0.2	0.3	0.1
Unfunded pension liability	$ 2.3