Stock-Based Compensation Plans - Securities Vested and Expected to Vest (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total Options and Non-Options Equity Instruments, Vested, Outstanding, Number	228,508
Total Options and Non-Options Equity Instruments, Expected to Vest, Outstanding, Number	172,690	[1]
Total Options and Non-Options Equity Instruments, Vested, Outstanding, Aggregate Intrinsic Value	$ 5,799	[2]
Total Options and Non-Options Equity Instruments, Expected to Vest, Outstanding, Aggregate Intrinsic Value	8,012	[1],[2]
Common stock, price per share	$ 47.35
2004 LTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, Vested, Outstanding, Number	17,376
Options, Expected to Vest, Outstanding, Number	0	[1]
Options, Vested, Outstanding, Weighted-Average Remaining Contractual Term (years)	1 year 3 months 18 days
Options, Expected to Vest, Outstanding, Weighted-Average Remaining Contractual Term (years)	0 days	[1]
Options, Vested, Outstanding, Aggregate Intrinsic Value	216	[2]
Options, Expected to Vest, Outstanding, Aggregate Intrinsic Value	0	[1],[2]
2005 LTIP [Member] | Restricted stock units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity Instruments Other than Options, Vested, Outstanding, Number	3,053
Equity Instruments Other than Options, Expected to Vest, Outstanding, Number	0	[1]
Equity Instruments Other than Options, Vested, Outstanding, Aggregate Intrinsic Value	145	[2]
Equity Instruments Other than Options, Expected to Vest, Outstanding, Aggregate Intrinsic Value	0	[1],[2]
2007 LTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, Vested, Outstanding, Number	169,107
Options, Expected to Vest, Outstanding, Number	0	[1]
Options, Vested, Outstanding, Weighted-Average Remaining Contractual Term (years)	2 years 6 months
Options, Expected to Vest, Outstanding, Weighted-Average Remaining Contractual Term (years)	0 days	[1]
Options, Vested, Outstanding, Aggregate Intrinsic Value	3,675	[2]
Options, Expected to Vest, Outstanding, Aggregate Intrinsic Value	0	[1],[2]
2007 LTIP [Member] | Restricted stock units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity Instruments Other than Options, Vested, Outstanding, Number	24,920
Equity Instruments Other than Options, Expected to Vest, Outstanding, Number	0	[1]
Equity Instruments Other than Options, Vested, Outstanding, Aggregate Intrinsic Value	1,180	[2]
Equity Instruments Other than Options, Expected to Vest, Outstanding, Aggregate Intrinsic Value	0	[1],[2]
2007 LTIP [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity Instruments Other than Options, Vested, Outstanding, Number	8,453
Equity Instruments Other than Options, Expected to Vest, Outstanding, Number	0	[1]
Equity Instruments Other than Options, Vested, Outstanding, Aggregate Intrinsic Value	400	[2]
Equity Instruments Other than Options, Expected to Vest, Outstanding, Aggregate Intrinsic Value	0	[1],[2]
2010 LTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, Vested, Outstanding, Number	2,500
Options, Expected to Vest, Outstanding, Number	5,000	[1]
Options, Vested, Outstanding, Weighted-Average Remaining Contractual Term (years)	5 years 9 months 18 days
Options, Expected to Vest, Outstanding, Weighted-Average Remaining Contractual Term (years)	5 years 9 months 18 days	[1]
Options, Vested, Outstanding, Aggregate Intrinsic Value	36	[2]
Options, Expected to Vest, Outstanding, Aggregate Intrinsic Value	73	[1],[2]
2010 LTIP [Member] | Restricted stock units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity Instruments Other than Options, Vested, Outstanding, Number	1,733
Equity Instruments Other than Options, Expected to Vest, Outstanding, Number	118,393	[1]
Equity Instruments Other than Options, Vested, Outstanding, Aggregate Intrinsic Value	82	[2]
Equity Instruments Other than Options, Expected to Vest, Outstanding, Aggregate Intrinsic Value	5,605	[1],[2]
2010 LTIP [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity Instruments Other than Options, Vested, Outstanding, Number	1,366
Equity Instruments Other than Options, Expected to Vest, Outstanding, Number	49,297	[1]
Equity Instruments Other than Options, Vested, Outstanding, Aggregate Intrinsic Value	65	[2]
Equity Instruments Other than Options, Expected to Vest, Outstanding, Aggregate Intrinsic Value	$ 2,334	[1],[2]

[1] Options, restricted stock units and performance shares that are expected to vest are net of estimated future forfeitures.

[2] Aggregate intrinsic value is calculated based upon the difference between the exercise prices of options or restricted stock units and our closing common stock price on December 31, 2012 of $47.35, multiplied by the number of instruments that are vested or expected to vest. Options and restricted stock units having exercise prices greater than the closing stock price noted above are excluded from this calculation.