Consolidated Statements of Cash Flows (USD $)
In Thousands, unless otherwise specified
 9 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Cash flows from operating activities:    
Net income $ 37,707 $ 46,539
Adjustments to reconcile net income to net cash provided by operating activities:    
Depreciation, depletion and amortization 67,273 66,676
Non-cash employee stock compensation expense 3,660 1,289
Gain on distribution to non-controlling interest   (259)
Amortization of debt discount 7,624 7,138
Impairment of royalty and stream interests 28,339  
Tax benefit of stock-based compensation exercises (74) (320)
Deferred tax benefit (34,199) (13,002)
Changes in assets and liabilities:    
Royalty receivables 7,168 8,175
Prepaid expenses and other assets 4,471 12,329
Accounts payable (1,742) 194
Foreign withholding taxes payable (2,001) (11,533)
Income taxes payable (receivable) 25,191 (4,551)
Other liabilities 4,777 2,411
Net cash provided by operating activities 148,194 115,086
Cash flows from investing activities:    
Acquisition of royalty and stream interests (60,341) (79,692)
Tulsequah stream termination 10,000  
Other (71) 227
Net cash used in investing activities (50,412) (79,465)
Cash flows from financing activities:    
Net proceeds from issuance of common stock 775 561
Common stock dividends (41,712) (39,706)
Purchase of additional royalty interest from non-controlling interest   (11,522)
Debt issuance costs   (1,284)
Distribution to non-controlling interests (1,227) (1,913)
Tax expense of stock-based compensation exercises 74 320
Net cash used in financing activities (42,090) (53,544)
Net increase (decrease) in cash and equivalents 55,692 (17,923)
Cash and equivalents at beginning of period 659,536 664,035
Cash and equivalents at end of period $ 715,228 $ 646,112