Leases (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating Leased Assets [Line Items]
Rent expense	$ 12,900,000	$ 12,700,000	$ 14,200,000
Total sublease income	700,000
Future minimum lease payments under capital leases [Abstract]
2013	1,330,000
2014	951,000
2015	41,000
2016	0
2017	0
2018 and thereafter	0
Total minimum lease payments	2,322,000
Less amount representing interest	(156,000)
Present value of minimum lease payments	2,166,000
Less current portion	(1,207,000)
Future minimum lease payments, net of current portion	959,000
Future minimum lease payments under operating leases [Abstract]
2013	14,062,000
2014	11,816,000
2015	10,675,000
2016	9,508,000
2017	9,183,000
2018 and thereafter	41,634,000
Total minimum lease payments	96,878,000
Corporate Headquarters and Call Center [Member]
Operating Leased Assets [Line Items]
Area of leased property (in square feet)	264,000
Lease expiration date	Feb. 28, 2023
Operating lease term	15 years
Tenant improvement allowance	10,300,000
Corporate Headquarters and Call Center [Member] | Minimum [Member]
Operating Leased Assets [Line Items]
Rent expense	4,200,000
Corporate Headquarters and Call Center [Member] | Maximum [Member]
Operating Leased Assets [Line Items]
Rent expense	$ 6,300,000
Other Call Center Locations [Member]
Operating Leased Assets [Line Items]
Area of leased property (in square feet)	224,000
Other Call Center Locations [Member] | Minimum [Member]
Operating Leased Assets [Line Items]
Lease expiration date	Dec. 31, 2013
Other Call Center Locations [Member] | Maximum [Member]
Operating Leased Assets [Line Items]
Lease expiration date	Dec. 31, 2016
Operations Support and Training Offices [Member]
Operating Leased Assets [Line Items]
Area of leased property (in square feet)	40,000
Operations Support and Training Offices [Member] | Minimum [Member]
Operating Leased Assets [Line Items]
Lease expiration date	Dec. 31, 2014
Operations Support and Training Offices [Member] | Maximum [Member]
Operating Leased Assets [Line Items]
Lease expiration date	Dec. 31, 2020
Office Space in Chandler [Member]
Operating Leased Assets [Line Items]
Area of leased property (in square feet)	92,000