Fair value measurements (other financial instruments) (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Carrying value [Member]
Fair value measurements, other financial instruments [Line Items]
Loans and notes receivable from Safeguard distributors		$ 35,580	$ 23,278
Long-term debt	[1]	737,836	756,963
Carrying value [Member] | Cash [Member]
Fair value measurements, other financial instruments [Line Items]
Cash		85,512	76,574
Carrying value [Member] | Funds held for customers [Member]
Fair value measurements, other financial instruments [Line Items]
Cash		66,485	66,289
Fair value [Member]
Fair value measurements, other financial instruments [Line Items]
Loans and notes receivable from Safeguard distributors		31,434	21,145
Long-term debt	[1]	738,750	758,000
Fair value [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Fair value measurements, other financial instruments [Line Items]
Loans and notes receivable from Safeguard distributors		0	0
Long-term debt	[1]	0	0
Fair value [Member] | Significant other observable inputs (Level 2) [Member]
Fair value measurements, other financial instruments [Line Items]
Loans and notes receivable from Safeguard distributors		0	0
Long-term debt	[1]	738,750	758,000
Fair value [Member] | Significant unobservable inputs (Level 3) [Member]
Fair value measurements, other financial instruments [Line Items]
Loans and notes receivable from Safeguard distributors		31,434	21,145
Long-term debt	[1]	0	0
Fair value [Member] | Cash [Member]
Fair value measurements, other financial instruments [Line Items]
Cash		85,512	76,574
Fair value [Member] | Cash [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Fair value measurements, other financial instruments [Line Items]
Cash		85,512	76,574
Fair value [Member] | Cash [Member] | Significant other observable inputs (Level 2) [Member]
Fair value measurements, other financial instruments [Line Items]
Cash		0	0
Fair value [Member] | Cash [Member] | Significant unobservable inputs (Level 3) [Member]
Fair value measurements, other financial instruments [Line Items]
Cash		0	0
Fair value [Member] | Funds held for customers [Member]
Fair value measurements, other financial instruments [Line Items]
Cash		66,485	66,289
Fair value [Member] | Funds held for customers [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Fair value measurements, other financial instruments [Line Items]
Cash		66,485	66,289
Fair value [Member] | Funds held for customers [Member] | Significant other observable inputs (Level 2) [Member]
Fair value measurements, other financial instruments [Line Items]
Cash		0	0
Fair value [Member] | Funds held for customers [Member] | Significant unobservable inputs (Level 3) [Member]
Fair value measurements, other financial instruments [Line Items]
Cash		$ 0	$ 0

[1] Amounts exclude capital lease obligations.