Stock Based Compensation - Deferred Stock Units Activty (Details) (Deferred Compensation, Share-based Payments, USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Deferred Compensation, Share-based Payments
Deferred Compensation Arrangement With Individual, Shares Outstanding [Roll Forward]
Number of deferred share units - as of beginning of year (US$)	22,147	0
Deferred share units - as of beginning of year (US$)	$ 49	$ 0
Deferred share units - grants (shares)	394,922	22,147
Deferred share units - grants (US$)	592	49
Deferred share units - exercises (shares)	(29,010)	0
Deferred share units - exercises (US$)	(39)	0
Number of deferred share units - as of end of year (US$)	388,059	22,147
Deferred share units - as of end of year (US$)	$ 602	$ 49